If I Had COVID, Why Should I Get Vaccinated?

After reading my article “Why Omicron Will Be The Last COVID Variant of (Major) Concern”, someone asked me about vaccination for people who have tested positive for the coronavirus, or who have actually had a symptomatic case of COVID19. Here is my reply.

The Questions:

Please help me know how to respond to people who don’t think they
need a vaccine because they have had Covid or tested positive without
symptoms. If someone gets one variant, does that mean they are covered
for all the variants? If they just have a positive test with no symptoms,
are they immune to all, any, or no variant?

These are hard questions because they don’t have yes/no answers.

The important underlying fact is, the immune system is not an on/off switch. You are not either “immune” or “not immune.” The immune system is more like a dimmer switch with an infinite number of settings. You can be slightly protected or very well protected or anything in between. You can have good protection against the lung disease of COVID but poor protection against infection in your nose. Or any combination you can imagine.

If someone has immunity against one variant of the coronavirus, they will have at least some coverage against all variants. How much their immune system protects them will depend partly on how much the variant has changed. You never hear about most variants because they are not variants “of concern.” They haven’t changed enough to escape the immune system. Future variants could be born that are better at escaping the immune system, but see my earlier article explaining why I’m not too worried about that causing us problems.

Immunity from previous infection: Is it enough?

If someone has a positive test with no symptoms, are they immune? What about if a person had COVID with symptoms?

Unfortunately there is no practical way to tell how strongly a person’s immune system learned from a natural infection in the past. We know that people’s immunity will vary in unpredictable ways. You can’t say, well that person got really sick so they should be very immune, or, that person hardly had any symptoms so they are not immune. In either case, they might have a great immune response, or they might still be quite vulnerable to another infection. We cannot tell.

Because of this variability and unpredictability, it is wise to get vaccinated even if you have had COVID or a positive test. The vaccine produces a more reliable immune response in people, so if your infection failed to rev up your immune system, the vaccine will.

However, it’s entirely possible that people who had COVID already don’t actually need a vaccine and they won’t get any additional benefit from it. So in a sense they are not “wrong” to refuse it. The problem is, they cannot actually know whether the vaccine will benefit them or not. So I would just get it to be safe.

Immunity decreases over time

The more important question is, how long ago was the infection? Immunity against the coronavirus that causes COVID appears to decline over time. If someone was infected in 2020 or first half of 2021, they almost certainly would benefit from vaccination or a booster shot because their immune response against the virus will have weakened considerably since then. For that reason, everyone, regardless of previous exposure to a natural COVID infection, should expect to keep their vaccination status up to date with recommended boosters in the future.

Questions? amy@amyrogers.com

Amy Rogers, MD, PhD, is a Harvard-educated scientist, novelist, journalist, and educator. Learn more about Amy’s science thriller novels at AmyRogers.com.