Does the CDC study on prior COVID infection vs vaccine really say "natural immunity" is better?

A recent CDC study is being grossly misrepresented by anti-vaxxers to say "natural immunity" is better. There's more to this than meets the eye.

Hi everyone,

I’m sure you have seen tweets and other posts like the following on social media and news:

Rupali Chadha, M.D.🩺 @RupaliChadhaMD

Breaking: CDC study finds natural immunity provides significantly more protection than mRNA pretreatment alone.

This refers to a recent CDC study that investigated examined COVID cases and hospitalizations in New York and California by vaccination status. Anti-vaxxers have seized that study to say “oh look CDC finally admits natural immunity is better than the vaccine”. Uhh, no, this is a massive misrepresentation. The CDC even had to put out a statement to clarify this. Let’s talk about it.

But before that, let me briefly tell you what this study found. Basically, this study looked at COVID-19 cases and hospitalizations in California and New York from May-Nov, 2021 (before and after the Delta variant was dominant in the US).

I won’t bore you with the actual numbers, but basically what they found was the following:

• Throughout the study period, COVID cases and hospitalizations were highest in people that were unvaccinated and never had COVID before (big surprise here). The graph above is a striking representation of this.

• Compared to those unvaccinated with no prior COVID: vaccinated (no infection) people had much lower case rates (20x lower). Not vaccinated but with prior infection: ~7-10x lower; vaccinated and prior infection: ~9-10x lower.

• Once the Delta variant became dominant in the fall, the numbers flipped. Compared to the unvaccinated without prior infection, those unvaccinated with prior infection had lower case rates (15-29x lower) than those who were vaccinated but did not have a prior infection (6x lower).

• However, during the time Delta was dominant, those that were vaccinated AND and a prior COVID infection had SIGNIFICANTLY reduced case rates (~20-30x lower), compared to the unvaccinated without prior COVID infection, and those who were unvaccinated but had had COVID before.

Anti-vaxxers have run with the above results, proudly proclaiming that the “CDC finally admits” that “natural immunity” is better than the vaccine. But in true fashion, they misrepresent the study and conveniently omit some very important points that we all need to consider.

First, I think it’s funny that these folks suddenly trust the CDC when during this entire pandemic they’ve been slamming the agency and consistently refusing to believe all of the pro-vaccine studies they have put out. Second, ALL immunity is natural, whether from infection or the vaccine.

1. No one has denied the existence of immunity from prior infection

No one has ever denied the existence of immunity from infection. We know that infection DOES provides some degree of immunity. We just don’t know how long that lasts, or how durable it is, or if EVERYONE will get the same degree of immunity. The vaccine on the other hand, generates immunity that is robust, reliable, and consistent.

2. COVID infection is a risky way to get immunity - 850,000 people did not survive.

Third, immunity from COVID infection is not without risk! You only get immunity if you SURVIVE COVID infection. The study appropriately calls people with prior infection COVID survivors. The 850,000+ people who have died in the US from COVID are not around to tell you their side of the story. Moreover, you also put yourself at risk of complications from COVID infection, such as lasting organ damage and long COVID which can be debilitating. Millions of people in the US and far more worldwide are suffering from long COVID, and we still don’t have good treatments for that yet.

The vaccine is a much SAFER way to gain immunity without putting yourself at risk of death from COVID or the complications of COVID including long COVID.

3. Vaccine immunity tends to wane over time

Third, what these folks don’t tell you, which the above data show you, is that BEFORE Delta became predominant, immunity from prior infection was inferior to the vaccine. Once the Delta variant become dominant, we started to learn that that people that had been vaccinated several months ago were starting to have waning immunity to infection. And because some of these folks didn’t have the immunity from having had infection, they were at higher risk of catching COVID (but were still protected from severe disease, hospitalization and death, thanks to the vaccine).

4. This study did not evaluate the efficacy of booster doses

Going on from the last point, this study did not evaluate the effectiveness of booster doses because they were not widely implemented during the study period. We know 4-6 months after a 2-dose vaccine, immunity tends to decrease (this is not a big surprise or hidden thing). Getting a booster dose significantly improves that protection. If this study had evaluated the impact of booster doses, we may have had different results.

5. No details on severity of infection

From this study alone, we do not have any details on the severity of infection of people who were infected. This is important because if you only have mild infection, you may not generate as robust an immune response as someone who had a bad case of COVID. Further, there are people (small studies show this) that do not generate any significant immune response at all from natural infection. On the other hand, except in the immunocompromised, the vaccine generates robust, reliable, consistent immunity across the board.

6. Hybrid immunity (both infection and vaccine) is the best.

The study found that getting vaccinated and having had infection provides the BEST protection. Anti-vaxxers won’t point that fact out. Why? Because it encourages people to get vaccinated.

7. This study is not applicable to the Omicron variant

This is perhaps the most relevant point here. The Omicron variant is now responsible for >95% of all cases in the US. This CDC study is only applicable to the time before Omicron. There is strong evidence at this point that prior infection does not provide significant protection against the Omicron variant. The Omicron variant has significant immune-escape: meaning it can evade the body’s defenses. While immunity from the 2-dose vaccine is also reduced, it shoots right back up after a booster dose. This is an excellent review by Dr. Topol.

So if you hear anyone touting this study as a reason not to get vaccinated, please tell them it does not apply in current times, because this study is not relevant to the Omicron variant.

Bottom line

Here’s the bottom line.

You DO get immunity from natural infection, but it is likely not as reliable, robust or consistent as the vaccine. Not everyone who gets COVID will get the same degree of protection. COVID infection carries significant risks, including death, complications, and very importantly long COVID, which is going to be a chronic illness for millions of people.

This study does not apply to the Omicron variant, which is what we’re dealing with now. Prior infection does not protect significantly against Omicron, and the best way to be protected is to be vaccinated + boosted (if eligible).

It’s all about considering the risks of COVID infection vs the vaccine, and the vaccine is a MUCH safer way to gain protection, with a significantly reduced risk of infection, complications, and long COVID.

And please, for the love of God, PLEASE DO NOT TRY TO GET COVID ON PURPOSE TO GET “NATURAL IMMUNITY”. It is a really bad idea and can kill you.

Let me know your thoughts, and please do share this with friends and family!

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