Immunologist Answers Questions About COVID Vaccine

If we are ever to return to anything close to normal, then the world’s population must be immune to SARS-CoV-2, the virus that causes COVID-19. But with so many different vaccines in production, questions are undoubtedly going to be raised, like can I have a vaccine if I have participated in a trial testing other versions? And what if I’ve already had COVID, do I still need a vaccine?

A basic understanding of immunology can answer all of these questions. All COVID vaccines attempt to generate an immune response to the proteins that the virus needs to enter your cells. Either by using a harmless virus that carries the protein that mimics SARS-CoV-2 but does not replicate, or by using the genetic code for those proteins (a messenger RNA), the result is the same. The critical protein for stopping SARS-CoV-2 is displayed, recognized by the immune system, and the body produces antibodies and T cells that are then ready to stop future infections.

Is it okay to have a different second dose?

A booster shot improves the quality of the immune response and sends a reminder about the virus. It does not matter if the vaccine used to prime the immune system is different from the one used to boost, as long as they both contain the critical viral protein.

Booster shots are common, and the time interval between them varies. For example, a tetanus booster is recommended every ten years, while vaccines for hepatitis A or measles are wonders from a single shot; no need for a booster.

Only by studying the immune response in people who have been vaccinated can we know when and if more booster shots are needed. This will be determined by measuring the SARS-CoV-2 specific antibody and T cell responses in a blood sample. Certain groups, such as older people, may need a different reinforcement strategy, and this will take time to resolve.

What if I already had a trial vaccine?

If you’ve participated in a COVID vaccine trial, it could give you a head start on the prime / boost approach, and you could reach the required immunity threshold faster. Alternatively, your test vaccination may have been so effective that the no-test version of the vaccine is not necessary.

It is important for vaccine developers to follow up with people who have received the vaccine to see how their immune systems have reacted and whether the vaccine gave them immunity or not. This follow-up should take place over a long period of time and cover different sections of the population: the young, the elderly, different ethnic groups, and patients taking drugs that weaken the immune system (such as chemotherapy).

What if I have had COVID?

Even if you have recovered from COVID-19, you can still benefit from vaccination. There is evidence in hospitalized patients that the infection was so overwhelming that the immune response was depleted, and therefore the memory immune to the virus was not created efficiently. Also, if you had a very mild infection, your immune system may not have reached the point of establishing immune memory. Therefore, vaccination could be beneficial, regardless of whether you experienced a severe or mild illness.

Although vaccination is an option, don’t forget that vaccines have been around for a long time and have saved more lives than any other medicine. The risk of contracting COVID and its dire side effects, often long-term, outweigh any theoretical risk from a vaccine.

This article is republished from The Conversation under a Creative Commons license. Read the original article.