Natural immunity vs vaccination

The pandemic seems to have been on forever, but we still have much to learn about COVID-19, which is only a bit over 2 years old, an infant among human diseases.  So it is unsurprising to have different opinions and debates and changes in positions.  Even scientists and medical professionals don’t agree on everything or many things, no wonder the public is often confused.

Take Dr John Campbell, a very popular YouTuber on COVID-19 subjects, as an example.  From his background he knows medical stuff more than the intricacy of science.  Most what he says fits the mainstream consensus, but two “obsessions” of his, one about ivermectin, and one about natural immunity, merit mentioning.

The case for ivermectin is odd.  Hyped by many people including Campbell, there is no clinical evidence it works against COVID-19.  Research cited by Campbell is of questionable quality, rebutted by no less than other YouTubers, and it is clear that the canonical mechanism of ivermectin won’t do because the lung concentration of ivermectin isn’t high enough.  The only saving grace for ivermectin supporters is that ivermectin might work with a different yet unknown mechanism.  But if that argument is enough, what is stopping tens of thousands of other medicines from ever being COVID-19 drugs?

Campbell is not against vaccination, but he places a higher premium on natural infection and immunity than probably most scientists and doctors would, especially since Omicron.  Campbell bets that Omicron infects everybody to give everybody immunity, then everybody will be free of COVID-19 forever.  This position fits the inclination of a large section of the populace, is not necessarily wrong, but also not necessarily right, either.  Unlike popular beliefs, the medical community has evaluated natural immunity vs vaccination.  The latest data, from CDC, cited as evidence is https://www.cdc.gov/mmwr/volumes/71/wr/mm7104e1.htm.  The study found that COVID-19 conferred protection a bit better than two-dose vaccination in CA and NY.  But the data were limited, might not apply to elsewhere, the Omicron variant, or any future variants. 

The first question is, which is safer?  There is no debate here, even if COVID-19 kills only 0.5% or fewer of the infected, and vaccines do have side effects.  And even if you survive, you may develop long COVID.  So if one has a choice of natural infection/immunity or vaccination, don’t do natural immunity, certainly not if you are old or have other health problems.  Even Campbell agrees on this.  If you get COVID-19 and clear it, consider yourself lucky, but it is never a better option population-wise.  Unfortunately, attempts to compare between natural immunity and vaccination often veer to arguing against mass vaccination. 

The second is the most important: is natural immunity really better?  Natural immunity has been suspected and recognized from animal and human studies by mid 2020 (April 9, 2020 blog), so it is not something scientists have ignored.   In 2020 two big unknowns are how long does immunity last, and what is the Ab threshold for protection?  Both questions have been answered reasonably well in 2021.  Immunity, natural or vaccine, drops after a few months, but protection against serious disease lasts longer than against infection.  The Ab threshold for protection is quite low, since different vaccines, i.e., mRNA, Ad, protein based, and inactivated virus based, are similarly effective at preventing serious outcomes even as they induce different levels of Ab in humans.   

These properties muddle the water of whether natural immunity is truly better than vaccination because a study must find people who are infected or vaccinated at the same time and compare how many are infected and their outcomes.  Furthermore, what variants they are infected and re-infected matter.  Few if any study has had that high level of resolution, so it is premature to conclude natural immunity is better, provided one survives first. 

On a slightly different note, the same shortcoming pertains when comparing different vaccines in different countries and clinical trials.  If a country, e.g., the US, is having a lot of cases at the same time people are getting the shots, the difference in infection between the vaccinated and unvaccinated will appear fast and vast.  But if the shots come earlier than the COVID-19 wave, the vaccines may seem less effective, simply because more time has passed since the shots.  But the protective power against serious disease is more alike.   

Critically, natural immunity has more uncertainty than vaccination.  Vaccination’s uncertainty lies in individuals responding to the same, uniformed vaccines differently.  Natural immunity shares the same variation, but has its additional, unique features: how much virus you got initially to become infected, and how sick you were, which also depends on whether and how much you got medical care.  This adds overwhelming amount of unpredictability to natural immunity.  Currently it is surmised that those who were modestly or seriously sick develop better immunity, so people who are infected with few or no symptoms might not realize they are carriers and might have little Ab or natural immunity.  These people could account for 10-50% of the infected, but are likely under-sampled by the CDC or other studies.  Thus, it is erroneously based on those data to conclude that natural immunity is better. 

The last question is, what is the best way to protect infection and re-infection, by Omicron, another variant, or future variants?  Omicron is more infectious than other variants mostly because it better evades human’s immune response, so will people get Omicron over and over once the immunity wears off?  How long are we protected against infection and against serious disease?  How do we get to the COVID-19 endgame with immunity?  Are we waiting for natural immunity, or vaccine booster?  Since we know immunity wanes (protection against serious disease should eventually drop as well), and we don’t know what future infection will bring, it will be foolish to roll the dice with and emphasize natural infection/immunity.

PS: Here is a history of 2009 pandemic origin, with eerie similarity to or lessons for COVID-19:  https://www.the-scientist.com/infographics/timeline-investigating-the-origins-of-the-2009-pandemic-69519?utm_campaign=TS_DAILY_NEWSLETTER_2022&utm_medium=email&_hsmi=203964027&_hsenc=p2ANqtz-9PEnTx85tmo-ZB_Bj1AK_X1xN0Ntpzqk73S-Qmh4r8NuuIDxnqKbnSDHfE8njqaIxll0C1LK_xwhsZWRehkf5DvY1zeQ&utm_content=203964027&utm_source=hs_email.