Post-COVID natural immunity has limits

DEAR DR. ROACH

» How does one manage natural immunity to COVID-19 if one has an autoimmune disease? Take vitamin D3, zinc, etc.?

— J.K.S.

DEAR READER »

“Natural immunity” refers to the protection that is conferred after a natural infection, as opposed to vaccination. Studies have shown that protection from infection following a case of COVID-19 is about 80% to 85% for six months after infection. However, immunity to a different variant (such as the delta variant widely circulating at the time of this writing) from the one a person was infected with may be substantially less. It is unknown how long the immunity lasts after infection, but it is likely to wane with time.

There is no good evidence that vitamin D supplementation reduces the likelihood of getting COVID-19 or getting a milder case or that it increases immunity. Similarly, zinc and vitamin C are undergoing further study, but there are not good data showing effectiveness as treatment or preventive for these supplements.

Autoimmune disease such as autoimmune thyroid disease does not increase the risk of a bad outcome with COVID-19. This is in contrast to immune deficiencies such as HIV or many of the primary immune deficiencies, which do confer risk of a worse outcome with COVID-19 and are likely to decrease the protection following vaccination or a natural infection that a person survives.

However, medications to treat autoimmune diseases often lead to greater risk — and less immunity to COVID-19. That’s because these medications cause a degree of immunosuppression. Some medicines are much more likely to do so than others. Unfortunately, supplements have not been proven of value.

Because there are many people undergoing treatment for autoimmune diseases, or who have immune deficiencies (including those caused by treatment of cancer and other diseases), vaccination and natural immunity are unable to protect everyone in a population. When there is ongoing community transmission, which as I write this is increasing in all 50 states, additional protective measures, such as social distancing and mask wearing, are necessary.