Health

COVID-19: Are antibodies the answer?

Governments worldwide are desperate to identify those who have recovered and developed antibodies against the novel coronavirus (SARS-CoV-2) that causes COVID-19 

 
By Vibha Varshney
Last Updated: Tuesday 23 June 2020
India’s sero-survey results were released on June 10 and it was found that only 0.73 per cent people in areas outside containment zones had antibodies Photo: Vikas Choudhary

The idea that those who have had the novel coronavirus disease (COVID-19) will, indeed, be immune to the SARS-CoV-2 virus that causes it, is fraught with scientific, ethical and legal issues. Immunity offers hope and reassurance. So, governments worldwide are desperate to identify those who have recovered and developed antibodies against SARS-CoV-2.

Some say this could serve as the basis for an ‘immunity passport’ that would enable individuals to travel or to return to work assuming they are protected against re-infection. Chile is poised to become the first country to provide such certificates to recovered COVID-19 patients, which will be valid for three months.

In March, Germany tested its population for immunity against COVID-19 using the rapid test kit. In Gangelt municipality, 14 per cent of the 500 people tested were found to have antibodies against SARS-CoV-2.

Swab tests showed two per cent were sick. Based on the findings, Germany planned to conduct serological tests across the country to issue immunity certificates so that people could resume work. But on May 5, 2020, it decided not to go ahead unless the study is cleared by its ethics council.

Alexandra L Phelan, professor at the microbiology and immunology department and an adjunct professor of law at the Georgetown University Law Center, US, wrote in The Lancet on May 4 that the potential discriminatory consequences of immunity passports may not be expressly addressed by existing legal regimes, because immunity from disease (or lack thereof) as a health status is a novel concept for legal protections.

In their column in New York Times, Kenneth Roth, executive director of Human Rights Watch and Annie Sparrow, a critical-care pediatrician and assistant professor of population health science and policy at the Icahn School of Medicine at Mount Sinai, US, wrote that employers might insist on antibody certificates simply to minimise absenteeism or medical costs among their workers; employees may find it easier to work with colleagues who have antibody certificates rather than to continue with face masks and social-distancing.



Note: Figures for Santa Clara, Los Angeles for April; rest for May; Sources: Government reports; *study by Stanford University, US, researchers published on MedRxia on April 30; **press release by University of Southern California, April 20But in this fight some are willing to make sacrifices. These are the countries that hope to achieve ‘herd immunity’ naturally. The debate around their quest is so intense that ‘herd immunity’ along with 30-odd other words and phrases related to the pandemic has made its way into Oxford Dictionaries (online version) in recent weeks.

Herd immunity

The dictionary defines herd immunity as “protection from a disease that happens if a large percentage of the population is immune to it”. Proponents believe once adequate immunity develops in a population, the spread of COVID-19 would stop.

Vaccines are usually used to create such herd immunity against infectious diseases like measles, mumps, polio and chickenpox.

But can we actually bank on our own immunity system to tide over the pandemic? If yes, to what extent? Researchers are racing against time to find the answers.

An analysis by the Center for Infectious Disease Research and Policy, US, made public on April 30, said COVID-19 is not likely to be halted until 60 to 70 per cent of the population is immune. However, studies on isolated populations show no city has so far managed to achieve this magical state.

India’s sero-survey results were released on June 10 and it was found that only 0.73 per cent people in areas outside containment zones had antibodies. This leaves the major population of country susceptible to the disease.

In Spain, the fourth worst-hit nation in the pandemic, the government launched a rapid serology test on April 27 to gauge the exposure of people to SARS-CoV-2.

It found only 11.3 per cent and 7.1 per cent people developed antibodies against COVID-19 in Madrid and Barcelona, which have paid the highest price in fatalities. In the last week of April, New York city, the epicentre of the pandemic in the US, also launched an antibody study by testing 15,000 people at grocery stores and community centres across the state.

Its findings show 12.3 per cent people now have COVID-19 antibodies. A similar study by the city government of Boston, Massachusetts in the US, found 9.9 per cent people have antibodies against COVID-19. In UK, the COVID-19 Surveillance Report showed14.8 per cent people in London had antibodies against COVID-19.

Sweden, which has not imposed lockdown, is hopeful that herd immunity would see it through the pandemic. When COVID-19 broke out there, towards the end of February, the government issued guidelines banning gatherings of over 50 people.

Restaurants, schools and parks remained open. It estimated that in Stockholm 60 per cent people would develop antibodies against the virus by May-June. But its Public Health Agency says only 7.3 per cent people have developed antibodies by the end of April.

Speaking to local media, Anders Tegnell, the country’s chief epidemiologist and brain behind the strategy, said, “Either the calculations made by the agency and myself are quite wrong...or more people have been infected than developed antibodies.”

Naturally developed immunity following a sickness is dicey. Even if adults develop immunity against the disease — a study posted on medRxiv on March 30 said older patients develop more antibodies against COVID-19 than the younger ones — it can circulate among children and infect those with weakened immune systems.

Besides, there is no evidence to show how long the immunity would protect from COVID-19. Other viruses like the flu mutate over time. So antibodies from a previous infection provide protection for less than a year.

Re-infections

In case of COVID-19, many patients who tested negative after treatment are testing positive again. As per one theory, these people getting reinfected might have developed low immunity during the first round of infection. But there is no conclusive evidence on this.

When researchers from China tried to reinfect the rhesus monkeys recovered from COVID-19 infection, they did not succeed. The monkeys developed immunity against the disease, says a study published on preprint server bioRxiv on March 13.

However, researchers at Fudan University, Shanghai, who studied blood samples from COVID-19 patients released after treatment, found nearly a third had low levels of antibodies. In some patients, antibodies could not be detected.

A paper published in Immunity on May 3, however, shed some light on how antibodies behave in people who had recovered from COVID-19. It compared the immune responses of 14 patients — eight recently discharged with six follow-up patients.

When compared with healthy controls, all recovered patients had higher levels of antibodies against COVID-19. But when compared among themselves, newly discharged patients had more antibodies than follow-up patients. But for how long would this immunity last? Will they get reinfected if exposed to high quantities of virus or their physical state weaken?

Scientists do not have answers to these probing questions so far.

It seems we have to live with the virus for some time even after a vaccine is ready.

Vaccines do not provide 100 per cent immunity. Flu vaccine, for one, is 59 per cent effective in adults and 27 per cent in keeping a person out of a hospital. A 2012 review says bcg vaccine, primarily used against tuberculosis, was 60 per cent effective in the first five years after inoculation.

The effectiveness decreased to 56 per cent between five and 10 years and to 46 per cent for up to 15 years. But vaccines against diphtheria are effective.

The COVID-19 vaccine has been put on a fast track and there are chances that it might not be tested very robustly. This can pose a serious risk.

In an interview with US-based natural health activist Joseph Mercola, Robert Kennedy Jr, an environmental lawyer and anti-vaxxer, narrated the problems with vaccines against coronavirus. He said they trigger the production of two kinds of antibodies.

While neutralising antibodies help fight the disease, the binding ones make the body more vulnerable. In 2012, four vaccines were tested on ferrets who showed good antibody response. But when they were exposed to the wild virus, they died.

This again happened in 2014 when dengue vaccine DenVax was administered on children in the Philippines. When they got infected with dengue, 600 of them died.

However, some communities may have an advantage over others when it comes to immunity. This natural defence mechanism of the body trains itself and evolves as people get constantly exposed to pathogens.

Being challenged daily with diseases like tuberculosis, malaria, dengue and chikungunya, Indians are more immune to infections compared to several other nationals. There is also evidence that Indians have evolved to gain more genes that protect them against viral infections.

“These genes enable natural killer (NK) cells, a type of white blood cells in our body that provide a first line of defense against viral infections,” said Rajalingam Raja, director of Immunogenetics and Transplantation Laboratory at the University of California in San Francisco, US.

Two families of genes, KIR genes and HLA genes, play a part in this protective function. Indians have more KIR genes than the Chinese and caucasians, said Raja in an article in Genes and Immunity in 2008.

He said Indians have also evolved to gain unique genes that regulate T and B cells, which produce specific and long-standing immunity to infection and could make Indians more immune to SARS-CoV-2.

However, authorities cannot take a decision on easing the lockdown based this special immunity of citizens. As Raja said, the number and type of genes are highly variable between individuals. “We do not know which gene is protecting from the SARS-COV-2 infection.”

The only options that the world has is to either wait for the vaccine to be developed or wait till populations become immune. Most researchers are in favour of taking precautions.

“India can take the decision guided by local data on infection rates,” said Gypsyamber D’Souza, epidemiologist with the Johns Hopkins Bloomberg School of Public Health, US.

“We should maintain the current levels of infection or even reduce the levels until a vaccine becomes available,” she added.

A vaccine is not to be available for at least a year. This means that people would need to practice physical distancing for an extended period. Given the population density and crowding, this would be a challenge in India.

This was first published in Down To Earth’s print edition (dated 15-30 June, 2020)

 

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