Developing antibodies are crucial in the fight against Covid-19. One can develop them by getting vaccinated or if they have been infected by the novel coronavirus. Just like soldiers protect a nation, antibodies are a specialised search-and-destroy army inside human bodies.
What are antibodies?
Antibodies help us fight off infections. It also protects us from getting the disease again. Antibodies are proteins created by our immune system soon after we are infected or vaccinated.
Coronavirus and Antibodies
In our fight against coronavirus infection, antibodies are a crucial weapon. When infected with Covid-19, a patient's body produces antibodies to fight off the infection.
These antibodies are known as immunoglobulins (IgM, IgA and IgG) and are key players in the response to Covid-19. Each has a unique role and takes different lengths of time to be detected in the blood, to reach the maximum quantity and diminish from the system. Most Covid-19 patients that do not display any symptoms have low levels of IgM, while levels of IgA and IgG antibodies are higher in more severe, symptomatic patients.
Tests for detecting antibodies:
Antibody or serology tests look for antibodies in the blood to determine if the individual had a past infection with the virus that causes Covid-19.
An antibody test may not show if you have a current infection because it can take 1–3 weeks after the infection for your body to make antibodies.
A negative antibody test, when done properly, shows that the individual may not have ever had Covid-19. A positive test result shows you may have antibodies from an infection with the virus that causes Covid-19.
How long will immunity to the novel coronavirus last?
A study by Rockefeller University (New York) claims that those who recover from Covid-19 are protected against the virus for at least six months, and likely much longer.
The findings, published in Nature in January, provide evidence that the immune system remembers the virus and, remarkably, continues to improve the quality of antibodies even after the infection has waned.
Antibodies produced months after the infection showed increased ability to block SARS-CoV-2, as well as its mutated versions. Based on these findings, researchers suspect that when the recovered patient next encounters the virus, the response would be both faster and more effective, preventing re-infection.
Similarly, researchers at Washington University School of Medicine in St. Louis says that antibodies can last for a lifetime. They say that even months after recovering from mild cases of COVID-19, people still have immune cells in their body pumping out antibodies against the virus that causes COVID-19. Such cells could persist for a lifetime, churning out antibodies all the while.
The study was published in the journal Nature on May 24. Senior author Ali Ellebedy, PhD, an associate professor of pathology & immunology, of medicine and of molecular microbiology says it's normal for antibody levels to go down after acute infection, but they don't go down to zero; they plateau.
He says their research found antibody-producing cells in people 11 months after first symptoms.
When our bodies have a viral infection, antibody-producing immune cells rapidly multiply and circulate in the blood, driving antibody levels sky-high. The study added that once the infection is resolved, most such cells die off, and blood antibody levels drop. A small population of antibody-producing cells, called long-lived plasma cells, migrate to the bone marrow and settle in, where they continually secrete low levels of antibodies into the bloodstream to help guard against another encounter with the virus.
Apart from these, scientists at the University of Utah carried out research, published in the journal Viruse in May. They say that within the next decade, coronavirus responsible for COVID-19 could become little more than a nuisance, causing no more than common cold-like coughs and sniffles. The findings suggest that changes in the disease could be driven by adaptations of our immune response rather than by changes in the virus itself.
The possible future is predicted by mathematical models that incorporate lessons learned from the current pandemic on how our body’s immunity changes over time. The models show that as more adults become partially immune, whether through prior infection or vaccination, severe infections all but disappear over the next decade. Eventually, the only people who will be exposed to the virus for the first time will be children — and they’re naturally less prone to severe disease.
For Yale scientists, immune system turncoats are one of the major culprits in severe cases of COVID-19. They say that the development of antibodies to the COVID-19 virus has been the great long-term hope of ending the pandemic. They added that some COVID-19 patients also develop antibodies that damage their own cells and tissues. In many cases the presence of coronavirus drove the creation of the damaging auto-antibodies. This study was also published this month in the journal Nature.
What happens after vaccination?
In India, so far, people have been given Covishield and Covaxin shots against the virus. As per Balram Bhargava, director-general of the Indian Council of Medical Research (ICMR), with the very first dose of Covishield vaccine, good levels of antibodies are produced in the body. However, with Covaxin, an adequate immune response is triggered only after the second dose.
A study by researchers at the University College London and published in Lancet claims that people who have previously had Covid-19 have an enhanced antibody response with a single dose of RNA vaccine.
It showed that a single dose of Pfizer/BioNTech's RNA vaccine (approved in the UK) resulted in a significantly enhanced immune response against the virus, compared to a single dose in those without prior infection. The findings, they say, have the potential to inform future vaccination strategies to include serology testing at the time of the first vaccination to enable the second, booster dose to be prioritised for previously uninfected individuals.
In those without prior infection, levels of spike-protein antibodies were similar to peak levels measured seen in individuals with mild SARS-CoV-2 infection.
However, those with prior infection produced high levels of antibodies against the spike protein after a single dose, compared to those without prior infection, indicating a significantly enhanced antibody response.
From a sample of 51 participants, 24 had a prior Covid-19 infection confirmed with a laboratory PCR test. Blood analysis of the 24 showed that antibody response increased 140-fold on average following a single dose of vaccine, compared to their peak pre-vaccine antibody levels – after their infection but before their first vaccination. Prior infections in this group date back to the beginning of the epidemic in London. The fact that a vaccine dose almost a year later has such a boosting effect, highlights the longevity of immune memory to this infection and increases our confidence that booster vaccines at intervals may be an effective way to may maintain high levels of immunity in the future
Another study, published in the BMJ, says that more than nine in 10 UK adults have antibodies to SARS-CoV-2 following one dose of the Oxford AstraZeneca or Pfizer BioNTech vaccine, while almost everyone does after a second dose. None had antibodies before receiving a first dose.