Tag Archives: Antibodies

Abbott wins U.S. emergency use authorization for new COVID-19 antibody test

(Reuters) – Abbott Laboratories said on Monday the U.S. Food and Drug Administration has issued an emergency use authorization for its lab-based COVID-19 antibody blood test.

The test, AdviseDx, can be used to identify a type of antibody called Immunoglobulin M (IgM) in blood samples to determine if someone has been exposure to the novel coronavirus, potentially indicating a recent or prior infection.

Abbott has already received emergency use authorization for seven tests, including molecular tests, a rapid antigen test and another test which can detect a type of antibody called IgG.

The FDA’s emergency use authorization allows the use of unapproved medical products in an emergency to diagnose, treat, or prevent serious or life-threatening diseases with no adequate or approved alternatives.

IgG is longer lasting in the body after an infection, but IgM is more useful for determining a recent exposure to the coronavirus as these antibodies become undetectable weeks to months following an infection, Abbott said.

Unlike molecular tests, which can detect whether someone has the coronavirus, antibody tests determine if someone has had a previous infection by detecting disease-fighting proteins called antibodies.

However, antibody tests are not recommended as the sole basis of diagnosis of COVID-19 as these antibodies may not be detected in the early days of the infection.

Shares of Abbott were up 0.5% at $110.21 in early trading.

(Reporting by Manojna Maddipatla in Bengaluru; Editing by Amy Caren Daniel)

Trump resumes campaign with Florida rally 10 days after COVID-19 disclosure

By John Whitesides

WASHINGTON (Reuters) – President Donald Trump will try to put his bout with COVID-19 behind him when he returns to the campaign trail on Monday, beginning a three-week sprint to the Nov. 3 U.S. election with a rally in the battleground state of Florida.

The event at an airport in Sanford, Florida, will be Trump’s first campaign rally since he disclosed on Oct. 2 that he tested positive for COVID-19. Trump, who spent three nights in the hospital for treatment, said on Sunday he had fully recovered and was no longer infectious, but did not say directly whether he had tested negative for the coronavirus.

For months, Trump had worked furiously to shift public attention away from the virus and his handling of the pandemic, which has infected nearly 7.7 million people in the United States, killed more than 214,000 and put millions out of work.

His own illness has put the spotlight squarely on his coronavirus response during the closing stretch of the race.

Trump’s rally in Florida, and planned rallies in Pennsylvania on Tuesday, Iowa on Wednesday and North Carolina on Thursday, will be watched closely to see whether the president has reshaped his campaign approach since contracting the virus.

Critics fault him for failing to encourage supporters at campaign events, and even White House staff, to wear protective masks and abide by social-distancing guidelines. At least 11 close Trump aides have tested positive for the coronavirus.

Standing alone on a White House balcony on Saturday, a maskless Trump urged hundreds of largely Black and Latino supporters to help get out the vote. Most in the crowd wore masks but ignored social-distancing guidelines.

Biden, who has said it is irresponsible for any candidate to hold events where attendees are not wearing masks or engaging in social distancing, lashed out at the president’s approach.

“President Trump comes to Sanford today bringing nothing but reckless behavior, divisive rhetoric, and fear mongering,” Biden, the Democratic former vice president said in a statement.

FLORIDA UP FOR GRABS

Trump told Fox News in an interview on Sunday that he felt good and pointed to his physician’s memo from Saturday saying he had taken a test showing he was no longer infectious.

“I passed the highest test, the highest standards, and I’m in great shape,” Trump told “Sunday Morning Futures.”

Trump also said, without producing evidence, that he was now immune, an assertion that drew a flag from Twitter for violating the social media platform’s rules about misleading information related to COVID-19.

The scientific research has been inconclusive on how long people who have recovered from COVID-19 have antibodies and are protected from a second infection.

Most recent polls in Florida, where a Trump loss would dramatically narrow his path to re-election, show Biden with a small lead. Trump won Florida over Democratic presidential nominee Hillary Clinton in 2016 by just 1.2 percentage points, which helped propel him to the White House.

On his visit to Ohio, Biden will deliver a speech in Toledo meant to undermine what polls show is Trump’s last greatest strength, the view among some voters that the former real estate entrepreneur is better on handling the economy.

Biden also will attend a get-out-the-vote event in Cincinnati, his campaign said.

Trump has pulled back his advertising in Ohio in recent days, while Biden has increased his, another sign of the opportunity he and his fellow Democrats see to make more states competitive than they initially imagined.

(Reporting by John Whitesides; Additional reporting by Trevor Hunnicutt and Jarrett Renshaw; Writing by John Whitesides and Paul Simao; Editing by Soyoung Kim, Peter Cooney and Howard Goller)

Scientists see downsides to top COVID-19 vaccines from Russia, China

By Allison Martell and Julie Steenhuysen

TORONTO/CHICAGO (Reuters) – High-profile COVID-19 vaccines developed in Russia and China share a potential shortcoming: They are based on a common cold virus that many people have been exposed to, potentially limiting their effectiveness, some experts say.

CanSino Biologics’ vaccine, approved for military use in China, is a modified form of adenovirus  type 5, or Ad5. The company is in talks to get emergency approval in several countries before completing large-scale trials, the Wall Street Journal reported last week.

A vaccine developed by Moscow’s Gamaleya Institute, approved in Russia earlier this month despite limited testing, is based on Ad5 and a second less common adenovirus.

“The Ad5 concerns me just because a lot of people have immunity,” said Anna Durbin, a vaccine researcher at Johns Hopkins University. “I’m not sure what their strategy is … maybe it won’t have 70% efficacy. It might have 40% efficacy, and that’s better than nothing, until something else comes along.”

Vaccines are seen as essential to ending the pandemic that has claimed over 845,000 lives worldwide. Gamaleya has said its two-virus approach will address Ad5 immunity issues.

Both developers have years of experience and approved Ebola vaccines based on Ad5. Neither CanSino nor Gamaleya responded to requests for comment.

Researchers have experimented with Ad5-based vaccines against a variety of infections for decades, but none are widely used. They employ harmless viruses as “vectors” to ferry genes from the target virus – in this case the novel coronavirus – into human cells, prompting an immune response to fight the actual virus.

But many people already have antibodies against Ad5, which could cause the immune system to attack the vector instead of responding to the coronavirus, making these vaccines less effective.

Several researchers have chosen alternative adenoviruses or delivery mechanisms. Oxford University and AstraZeneca based their COVID-19 vaccine on a chimpanzee adenovirus, avoiding the Ad5 issue. Johnson & Johnson’s candidate uses Ad26, a comparatively rare strain.

Dr. Zhou Xing, from Canada’s McMaster University, worked with CanSino on its first Ad5-based vaccine, for tuberculosis, in 2011. His team is developing an inhaled Ad5 COVID-19 vaccine, theorizing it could circumvent pre-existing immunity issues.

“The Oxford vaccine candidate has quite an advantage” over the injected CanSino vaccine, he said.

Xing also worries that high doses of the Ad5 vector in the CanSino vaccine could induce fever, fueling vaccine skepticism.

“I think they will get good immunity in people that don’t have antibodies to the vaccine, but a lot of people do,” said Dr. Hildegund Ertl, director of the Wistar Institute Vaccine Center in Philadelphia.

In China and the United States, about 40% of people have high levels of antibodies from prior Ad5 exposure. In Africa, it could be as high as 80%, experts said.

HIV RISK

Some scientists also worry an Ad5-based vaccine could increase chances of contracting HIV.

In a 2004 trial of a Merck & Co Ad5-based HIV vaccine, people with pre-existing immunity became more, not less, susceptible to the virus that causes AIDS.

Researchers, including top U.S. infectious diseases expert Dr. Anthony Fauci, in a 2015 paper, said the side effect was likely unique to HIV vaccines. But they cautioned that HIV incidence should be monitored during and after trials of all Ad5-based vaccines in at-risk populations.

“I would be worried about the use of those vaccines in any country or any population that was at risk of HIV, and I put our country as one of them,” said Dr. Larry Corey, co-leader of the U.S. Coronavirus Vaccine Prevention Network, who was a lead researcher on the Merck trial.

Gamaleya’s vaccine will be administered in two doses: The first based on Ad26, similar to J&J’s candidate, and the second on Ad5.

Alexander Gintsburg, Gamaleya’s director, has said the two-vector approach addresses the immunity issue. Ertl said it might work well enough in individuals who have been exposed to one of the two adenoviruses.

Many experts expressed skepticism about the Russian vaccine after the government declared its intention to give it to high-risk groups in October without data from large pivotal trials.

“Demonstrating safety and efficacy of a vaccine is very important,” said Dr. Dan Barouch, a Harvard vaccine researcher who helped design J&J’s COVID-19 vaccine. Often, he noted, large-scale trials “do not give the result that is expected or required.”

(Additional reporting by Christine Soares in New York, Kate Kelland in London, Polina Ivanova in Moscow and Roxanne Liu in Beijing; Editing by Caroline Humer and Bill Berkrot)

Novavax starts enrollment for phase two of COVID-19 vaccine trial

(Reuters) – Novavax Inc said on Monday it has begun enrolling volunteers for the second phase of an ongoing clinical trial of its COVID-19 vaccine candidate, with interim data expected in the fourth quarter of 2020.

In the new phase, the age range has been expanded, with adults between 60 and 84 years accounting for nearly 50% of the trial’s population.

Early-stage data from a small clinical trial of the vaccine has shown it produced high levels of virus-fighting antibodies, and the company aims to begin larger studies to obtain regulatory approvals as early as December.

The vaccine candidate is one of nearly 30 being tested in human clinical trials globally and lags candidates from AstraZeneca, Pfizer and Moderna that are in late-stage studies.

The U.S. government in July awarded Novavax $1.6 billion to test and manufacture its vaccine in the United States, with the aim of delivering a 100 million doses by January.

Britain has also tied-up with the company to buy 60 million doses of its vaccine candidate, some of which will be made using Fujifilm Diosynth Biotechnologies facilities in Stockton-on-Tees, northern England.

The study is targeting enrollment of up to 1,500 healthy volunteers at up to 40 sites in the United States and Australia, Novavax said.

Last week, the drug developer began a mid-stage study of its COVID-19 vaccine in South Africa.

(Reporting by Ankur Banerjee and Vishwadha Chander in Bengaluru; Editing by Arun Koyyur)

What you need to know about the coronavirus right now

(Reuters) – Here’s what you need to know about the coronavirus right now:

Concerns grow that kids spread virus

U.S. students are returning to school in person and online in the middle of a pandemic, and the stakes for educators and families are rising in the face of emerging research that shows children could be a risk for spreading the new coronavirus.

Several large studies have shown that the vast majority of children who contract COVID-19, the disease caused by the virus, have milder illness than adults. And early reports did not find strong evidence of children as major contributors to the deadly virus that has killed more than 780,000 people globally.

But more recent studies are starting to show how contagious infected children, even those with no symptoms, might be.

Grave situation in renewed South Korea outbreak

Novel coronavirus infections have spread nationwide from a church in the South Korean capital, raising fears that one of the world’s virus mitigation success stories might yet suffer a disastrous outbreak, a top health official said on Thursday.

“The reason we take the recent situation seriously is because this transmission, which began to spread around a specific religious facility, is appearing nationwide through certain rallies,” Vice Health Minister Kim Gang-lip told a briefing.

The positive cases from the rallies include people from nine different cities and provinces across the country. Kim did not identify those places but said 114 facilities, including the places of work of infected people, were facing risk of transmission.

Brazil sees signs spread is slowing

The spread of the coronavirus in Brazil could be about to slow, the Health Ministry said, amid reports the transmission rate has fallen below a key level and early signs of a gradual decline in the weekly totals of cases and fatalities.

The cautious optimism comes despite figures again showing a steady rise in the number of confirmed cases and death toll in the last 24 hours, cementing Brazil’s status as the world’s second biggest COVID-19 hot spot after the United States.

According to ministry data, Brazil saw a drop in the number of new confirmed COVID-19 cases to 304,684 last week from a peak of 319,653 in the week ending July 25. The weekly death toll fell to 6,755 from a peak of 7,677 in the last week of July.

Trump touts convalescent plasma as treatment

U.S. President Donald Trump on Wednesday touted the use of convalescent plasma as a treatment for COVID-19 and suggested a reported decision by regulators to put on hold an emergency authorization for its use could be politically motivated. “I’ve heard fantastic things about convalescent plasma,” Trump told a briefing.

An emergency approval by the Food and Drug Administration (FDA) for the use of blood plasma as a coronavirus treatment has been put on hold over concerns the data backing it was too weak, the New York Times reported on Wednesday. The FDA did not respond to a request for comment.

People who survive an infectious disease such as COVID-19 are left with blood plasma containing antibodies the body’s immune system created to fight off a virus. This can be transfused into newly infected patients to try to aid recovery.

China backs Wuhan park after pool party

Chinese state newspapers threw their support behind an amusement park in the central city of Wuhan on Thursday after pictures of a densely packed pool party at the park went viral overseas amid concerns about the spread of COVID-19.

Videos and photos of an electronic music festival at the Wuhan Maya Beach Water Park on July 11 raised eyebrows overseas, but reflected life returning to normal in the city where the virus causing COVID-19 was first detected, the official English-language China Daily newspaper said in a front-page story.

Another story in the Global Times, a tabloid published by the ruling Communist Party’s People’s Daily, cited Wuhan residents as saying the pool party reflected the city’s success in its virus-control efforts.

(Compiled by Linda Noakes and Karishma Singh; Editing by Mark Potter)

FDA’s emergency approval of blood plasma as COVID-19 treatment on hold: NYT

(Reuters) – The emergency approval of blood plasma as a potential COVID-19 treatment by the U.S. Food and Drug Administration has now been put on hold, the New York Times reported on Wednesday, citing two senior administration officials.

A group of top federal health officials including Anthony Fauci have argued that the emerging data on the treatment was too weak, the report said, adding that an emergency approval could still be granted in the near future.

The authorization is on hold for now as more data is reviewed, the NYT reported, citing Clifford Lane, the clinical director at the National Institute of Allergy and Infectious Diseases, part of the National Institute of Health.

The FDA and NIH did not immediately respond to Reuters’ requests for comment.

People who survive an infectious disease like COVID-19 are left with blood plasma containing antibodies, or proteins the body’s immune system created, to fight off a virus. This can be transfused into newly infected patients to try to aid recovery.

An FDA emergency-use authorization could allow faster access to a therapy for the pandemic.

(Reporting by Trisha Roy in Bengaluru; Editing by Saumyadeb Chakrabarty)

Next big COVID-19 treatment may be manufactured antibodies

By Deena Beasley

(Reuters) – As the world awaits a COVID-19 vaccine, the next big advance in battling the pandemic could come from a class of biotech therapies widely used against cancer and other disorders – antibodies designed specifically to attack this new virus.

Development of monoclonal antibodies to target the virus has been endorsed by leading scientists. Anthony Fauci, the top U.S. infectious diseases expert, called them “almost a sure bet” against COVID-19.

When a virus gets past the body’s initial defenses, a more specific response kicks in, triggering production of cells that target the invader. These include antibodies that recognize and lock onto a virus, preventing the infection from spreading.

Monoclonal antibodies – grown in bioreactor vats – are copies of these naturally-occurring proteins.

Scientists are still working out the exact role of neutralizing antibodies in recovery from COVID-19, but drugmakers are confident that the right antibodies or a combination can alter the course of the disease that has claimed more than 675,000 lives globally.

“Antibodies can block infectivity. That is a fact,” Regeneron Pharmaceuticals executive Christos Kyratsous told Reuters.

Regeneron is testing a two-antibody cocktail, which it believes limits the ability of the virus’ to escape better than one, with data on its efficacy expected by late summer or early fall. “Protection will wane over time. Dosing is something we don’t know yet,” said Kyratsous.

The U.S. government in June awarded Regeneron a $450 million supply contract. The company said it can immediately begin production at its U.S. plant if regulators approve the treatment.

Eli Lilly and Co, AstraZeneca, Amgen, and GlaxoSmithKline were cleared by the U.S. government to pool manufacturing resources in order to scale up supplies if any of these drugs prove successful.

Even with that unusual cooperation among rivals, manufacturing these medicines is complex and capacity is limited. There is also a debate over whether a single antibody will be powerful enough to stop COVID-19.

AstraZeneca said it plans to start human trials of its dual-antibody combination within weeks.

Lilly, which began human testing in June of two antibody candidates in separate trials, is focusing on a one-drug approach.

“If you need a higher dosage or more antibodies, fewer people can be treated,” Lilly Chief Scientific Officer Dan Skovronsky said.

‘INSTANT IMMUNITY’

Unlike vaccines, which activate the body’s own immune system, the impact of infused antibodies eventually dissipates.

Still, drugmakers say monoclonal antibodies could temporarily prevent infection in at-risk people such as medical workers and the elderly. They could also be used as a therapeutic bridge until vaccines become widely available.

“In a prophylactic setting we think we may achieve coverage for up to six months,” said Phil Pang, chief medical officer of Vir Biotechnology, which aims to start testing an antibody in non-hospitalized patients next month with partner GSK.

“The advantage of an antibody is that it is basically instant immunity,” said Mark Brunswick, senior vice president at Sorrento Therapeutics, which aims to begin human trials next month of a single antibody candidate.

Safety risks for monoclonal antibodies are considered low, but their cost can be quite high. These type of drugs for cancer can cost over $100,000 a year.

There is also concern that the coronavirus could become resistant to specific antibodies. Researchers are already at work on second-generation compounds with targets other than the crown-like spikes the virus uses to invade cells.

“We are trying to develop something that is complementary,” Amgen research chief David Reese said. Amgen is working with Adaptive Biotechnologies Corp.

Researchers in a recent paper published in the journal Nature said they had discovered several new, very potent, antibodies directed to an area where the virus attaches to human cells and to a region of the spike that has not attracted attention.

“To avoid development of resistance you want to target different sites,” study author and Columbia University professor David Ho told Reuters.

There are also questions about when in the course of the illness it might be best to employ these new weapons.

“Giving an antibody later on after infection might not be that helpful, said Florian Krammer, microbiology professor at New York’s Icahn School of Medicine. “Given early, they probably work well.”

(Reporting By Deena Beasley, editing by Peter Henderson and Bill Berkrot)

Donated plasma benefits COVID-19 patients in small U.S. study

By Deena Beasley

(Reuters) – Patients with severe COVID-19 given plasma from someone who recovered from the disease were more likely to stabilize or need less oxygen support than other similar hospital patients, according to results of a small U.S. study released on Friday.

The study showed a trend toward better survival rates, but the number of patients was small and the results cannot be interpreted as applying to patients on mechanical ventilators, researchers at New York’s Mt. Sinai Medical Center said.

Mt. Sinai analyzed outcomes for 39 hospitalized patients with severe COVID-19 who received convalescent plasma transfusions compared to outcomes for patients with carefully matched medical status.

“This is a retrospective case-controlled study. It does not have the rigor of a randomized, controlled trial so that still needs to be done,” Dr. Nicole Bouvier, an infectious disease specialist at Mt. Sinai and the study’s lead author, told Reuters.

“This does show promise that convalescent plasma is effective.”

Nearly 70% of the 39 patients were on high-flow oxygen and 10% were on mechanical ventilation. After two weeks, the disease worsened in 18% of the plasma patients and 24% of the control patients.

As of May 1, nearly 13% of plasma recipients had died, compared with more than 24% of the control patients, with 72% and 67%, respectively, being discharged alive.

People who survive an infectious disease like COVID-19 are left with blood containing antibodies, or proteins made by the body’s immune system to fight off a virus. The blood component that carries the antibodies can be collected and given to newly infected patients – it is known as “convalescent plasma.”

Hospitals around the world have been using plasma donated by recovered COVID-19 patients, but there has been little information on how effective the treatment is.

The U.S. Food and Drug Administration on May 1 gave emergency approval to Gilead Sciences Inc’s antiviral drug remdesivir for COVID-19 based on data showing that it reduced hospitalization time by 31% compared to a placebo, but did not have a significant effect on survival.

(Reporting by Deena Beasley; Editing by Tom Brown)

U.S. employers wary of coronavirus ‘immunity’ tests as they move to reopen

By Caroline Humer and Timothy Aeppel

NEW YORK (Reuters) – U.S. employers have cooled to the idea of testing workers for possible immunity to the coronavirus as they prepare to reopen factories and other workplaces.

Blood tests that check for antibodies to the new coronavirus have been touted by governments and some disease experts as a way to identify people who are less likely to fall ill or infect others. Italian automaker Ferrari NV has made antibody testing central to its “Back on Track” project to restarting factories.

But many U.S. companies are not planning to use them, relying on face masks, temperature checks, social distancing, and diagnostic tests for those with symptoms, employers and healthcare experts told Reuters.

Mercer, which advises companies on healthcare benefits, has surveyed more than 700 U.S. employers in industries from high tech to retail to energy, and found 8% of companies said they would include antibody tests in plans to screen employees.

Interest in antibody tests from employers has fallen in recent weeks as reports have suggested that it is too early to conclude that antibodies to the new coronavirus translate into immunity. The American Medical Association cautioned on Thursday that these tests do not determine an individual’s immunity.

“Many employers … are realizing that antibody testing isn’t going to be a silver bullet and really isn’t going to bring them any value,” said David Zieg, a lead consultant on clinical services at Mercer.

Other employers worry about their liability if they administer and interpret such tests, or are concerned about test costs and availability. Some were spooked by a flood of tests that hit the market before being reviewed by regulators for accuracy, which has contributed to confusion over results.

A new antibody test from Roche Holding AG that has shown itself to be highly accurate could potentially help answer questions about antibodies and immunity and change corporate demand, but it has not done so yet, consultants and companies said.

Governments, however, are interested in antibody tests, particularly if they are accurate. Britain on Thursday said it is in talks with Roche over buying tests that it could use to create a certificate of immunity once there is a better understanding of the science.

Collective Health, a healthcare technology company that has built back-to-work strategies for large companies, is advising employers to use diagnostic tests, not antibody tests.

“There has been a proliferation of low-quality antibody tests and the antibody tests themselves don’t necessarily answer any questions about immunity,” said Rajaie Batniji, Collective Health’s chief health officer.

GETTING BACK TO WORK

When General Motors Co, Ford Motor Co and Fiat Chrysler Automobiles NV reopen production next week, they intend to offer diagnostic tests to workers, not antibody tests. Officials at the Detroit carmakers said it was because it was not clear what the antibody tests show.

Amazon.com Inc’s on-site testing plan, now in development, does not include antibody testing. Those views were echoed in interviews with a handful of smaller U.S. manufacturers.

Shawn Kitchell, chief executive of Florida-based plastics manufacturer Madico Inc, is not planning to use antibody tests for his 250 employees. He questions their costs, accuracy, and the fact that the timing of tests can lead to different results, requiring multiple tries.

“How frequently would we need to test to make it safer for our co-workers?” Kitchell said.

Employers are also wary of an unregulated U.S. market for antibody tests. Since March, the U.S. Food and Drug Administration (FDA) has allowed more than 200 tests into the market without regulatory review to make them available quickly, opening the door to questionable vendors and inaccurate tests, Reuters found.

Last week, the agency set a deadline for all vendors to prove to the FDA that their tests work or remove them from the market. It has also authorized two highly-accurate tests from Roche and Abbott Laboratories, which are able to supply millions of tests per week.

One of the biggest U.S. testing providers, LabCorp, on Thursday said it was rolling out a program to make diagnostic tests and antibody tests available at workplaces.

LabCorp’s chief medical officer, Brian Caveney, said interest in antibody testing is coming from companies in coronavirus hotspots, such as New York, while other areas with fewer COVID-19 cases see diagnostic testing as more important.

As the new FDA process shows which tests work and which don’t, that will help advance research on how many people recovering from COVID-19 develop antibodies and at what level, and show if they are truly immune to infection, said Howard Koh, a professor at the Harvard T.H. Chan School of Public Health.

“Until we go through those steps, I don’t see how we can translate this for the typical person who wants to go back to work,” Koh said.

(This story has been refiled to change spelling to Zieg from Zeig in paragraph six)

(Reporting by Caroline Humer, Timothy Aeppel and Krystal Hu in New York and Ben Klayman in Detroit; editing by Michele Gershberg and Nick Zieminski)

Most COVID-19 patients get antibodies but immunity unclear: UK official

LONDON (Reuters) – Studies in Britain show that most people who have had COVID-19 develop antibodies, England’s deputy chief medical officer Jonathan Van-Tam said on Monday, but it was too early to say whether this gave them immunity.

“The overwhelming majority of people so far called back who’ve had definite COVID-19 infection have got antibodies in their blood stream,” Van-Tam said at daily news conference.

“By and large the signal is that people get antibodies. The next question is, do those antibodies protect you from further infections. And we just haven’t had this disease around … for long enough to know the answers to that with any surety.”

Health Secretary Matt Hancock added that the government was in discussions with Swiss pharmaceutical firm Roche over antibody testing.

(Reporting by William James and Andy Bruce; writing by Alistair Smout; editing by Estelle Shirbon)