COVID-19 Immunity: For How Long?

Many studies try to determine how long the immunity lasts after a COVID-19 or SARS-CoV-2 infection. But it’s a question that can’t be answered for some time, said Dr. William Moss told Medical Daily.

“[Since] We are only 10 months after the pandemic … we still have a lot to learn, especially about long-term immunity, “said Dr. Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health.

A recent study by the University of Arizona (UA) found that immunity to COVID-19 infection can last at least five to seven months. In an article by UA, Deepta Bhattacharya, PhD, An associate professor of immunobiology said, although seven months is the longest time the study can confirm immunity persists, “We know that people infected with the first SARS coronavirus, the SARS-CoV 2 is most similar, immunity is still 17 years after infection. If SARS-CoV-2 is anything like the first, we’d expect antibodies to last for at least two years, and it’s unlikely anything much shorter than that. “

Let’s talk about immunity

Dr. Moss said the results of the UA trial are what he would expect at this point and there is hope for even longer immunity. “It is not unreasonable to expect immunity to this coronavirus to be similar to other coronaviruses. So we might expect people to be protected a year or two after being infected, but it is possible that people with severe SARS-CoV-2 could be protected longer [because] … you had a stronger immune response. For people who had a very mild or asymptomatic infection and didn’t know they were sick, it is possible that their immunity lasts as little as six months to a year. “

Another reason why immunity lasts longer or shorter for different people is because of what is known as “heterogeneity”, which means that we have different immune responses because our bodies are different. Older adults tend to have shorter periods of immunity after illness because their immune systems have aged and are not functioning as well as they were in younger years. People with health problems can also have a harder time building an immune response strong enough to fight a disease.

The vaccines

Although “a natural infection produces a stronger immune response than vaccines in general … we need to develop vaccines that are even better than natural immunity,” said Dr. Moss. One method that vaccine manufacturers use is to add adjuvants to a vaccine. Adjuvants help the vaccine produce a stronger immune response in the body. This is especially helpful for the elderly or chronically ill whose immune systems may not respond as strongly to a vaccine that doesn’t contain adjuvants, said Dr. Moss.

“I think we’ll know in November or December if some of these are early [vaccines] Work, “said Dr. Moss. “It may well be that the first vaccines approved are ultimately not the best. The [vaccines] For example, those messenger RNA vaccines that lead the prosecution were really easy to design and manufacture. While some of the inactivated virus vaccines are more difficult to manufacture. And some of them [inactivated vaccines] are those to which adjuvants have been added. “

But do you need a vaccine if you’ve already had the virus?

Dr. Moss said he had not seen guidelines for antibody testing related to vaccination against SARS-CoV-2. However, since we don’t know how long the antibody protection will last for this coronavirus, it is often easier to just vaccinate than to do in such situations [an antibody] test and then vaccinate, ”he said.

“It is possible that if [the vaccine’s] Protective immunity only lasts a year or two [we could see] a recommendation that people be vaccinated against SARS-CoV-2 every year or every two years. “

Could I Get COVID-19 Again?

In order to document a real reinfection with SARS-CoV-2, you would have to “genetically sequence the first virus and the second virus and show that they are different,” said Dr. Moss. “There were case reports of people who were re-infected with SARS-CoV-2 and who had a very well documented first and second infection. But I would expect that upon re-exposure, most people would have a very rapid, strong immune response that would limit the severity of the disease. “

He added, “I would say there is a very, very likely that if you test positive for an antibody test now, you are protected from serious illness, if not mild illness or even symptomatic infection.”

Take them home

It will be a while before we know how long immunity will last after a COVID-19 infection or vaccination against COVID-19. However, researchers are confident that immunity will last longer than they can currently measure.