Bill Maher ‘Natural Immunity’ Study Tweet

On February 19 2023, a Twitter user tweeted a quote (with video) from talk show host and comedian Bill Maher, on the subject of a “big study” on “natural immunity” and how it held up against vaccines:

Bill Maher’s ‘Natural Immunity’ Comments, and the ‘Liberal Media’

A link under the video led to a previous tweet with the same footage, dated February 17 2023. On February 20 2023, RealClearPolitics partially transcribed Maher’s comments in the video.

Fact Check

Claim: A “big study” in February 2023 indicated “natural immunity” was “as good or better” than immunity caused by vaccines.

Description: Comedian Bill Maher quoted a study’s findings that ‘natural immunity’ might be ‘as good or better’ than vaccination-caused immunity. This study was viewed by Maher as being possibly overlooked or misrepresented by the ‘liberal media’.

Rating: Decontextualized

Rating Explanation: The study Maher referred to did find that immunity from past infection should be considered in public health decisions. However, the study did not specifically mention it was ‘better’ than vaccine immunity. Furthermore, this study was covered by multiple news outlets.

In the excerpt, Maher mentioned a “giant study” with data obtained from “something like 65” countries. Maher further framed the information as reflecting “one side” of a two-sided perspective, which he maintained was misrepresented or unreported by the “liberal media”:

“[I’m not sure that was the best example because let me … let me try another one, because] I saw in the paper today, kind of a big story I think, I wonder how much it’s going to get covered in the liberal media. Because it’s about how natural immunity – they did a giant study, something like 65 [studies]. Many, many different studies, they looked at them all. Natural immunity, as good or better than the vaccine. Something I’ve been saying since the beginning and I get called an anti-vaxxer. That’s not an anti-vaxxer.

“This is the kind of thing — my problem with the media from both sides is not that you guys lie, it’s that you tell me your side of the story that you want me to know. You don’t tell me the whole story. I’d be curious to see how much play this story gets because I remember reading they did a study of Republicans vs. Democrats. The question was what percentage — this was like a year and a half ago — what percentage of people who get COVID require hospitalization? The answer is less than 1%. Almost half of Democrats thought it was over 50%. They listen to your network. Where do they get that kind of information? That’s bad information they have in their head and it is from one side … “

Maher’s mention of the “liberal media” referenced a widespread partisan belief that American news is biased against “conservative” viewpoints. In fact, a lengthy Wikipedia page about the concept was itself prefaced with a prominent warning that the neutrality of the page remained “disputed”:

bill maher big study liberal media natural immunity

Text underneath the warning summarized the page:

Media bias in the United States occurs when US media outlets skew information, such as reporting news in a way that conflicts with standards of professional journalism or promoting a political agenda through entertainment media. Claims of outlets, writers, and stories exhibiting both have increased as the two-party system has become more polarized, including claims of liberal and conservative bias. There is also bias in reporting to favor the corporate owners, and mainstream bias, a tendency of the media to focus on certain “hot” stories and ignore news of more substance. A variety of watchdog groups attempt to combat bias by fact-checking biased reporting and also unfounded claims of bias. Researchers in a variety of scholarly disciplines study media bias.

In April 2020, the American Association for the Advancement of Science’s Science Advances published “There is no liberal media bias in which news stories political journalists choose to cover,” with an abstract that challenged the notion of a “liberal media”:

Is the media biased against conservatives? Although a dominant majority of journalists identify as liberals/Democrats and many Americans and public officials frequently decry supposedly high and increasing levels of media bias, little compelling evidence exists as to (i) the ideological or partisan leanings of the many journalists who fail to answer surveys and/or identify as independents and (ii) whether journalists’ political leanings bleed into the choice of which stories to cover that Americans ultimately consume. Using a unique combination of a large-scale survey of political journalists, data from journalists’ Twitter networks, election returns, a large-scale correspondence experiment, and a conjoint survey experiment, we show definitively that the media exhibits no bias against conservatives (or liberals for that matter) in what news that they choose to cover. This shows that journalists’ individual ideological leanings have unexpectedly little effect on the vitally important, but, up to this point, unexplored, early stage of political news generation.

A ‘Big Study’ on Natural Immunity

The initial February 17 2023 tweet with video contained language claiming that “NBC News admitted Natural immunity is as good (or better) than vaccinated immunity for COVID 19,” implying that news networks were reluctant to publish information about the study in question — a foundational aspect of pandemic-related conspiracizing.

Maher almost immediately contradicted himself in the clip, introducing the study he “saw [reported] in the paper today, kind of a big story.” Then he pondered “how much it’s going to get covered in the liberal media,” presumably the same liberal media responsible for publishing his newspaper.

Maher’s show (Real Time with Bill Maher) airs on Fridays, and February 17 2023 was a Friday; one of the three panelists was Ari Melber of MSNBC. On February 16 2023, NBC News published, “Immunity acquired from a Covid infection is as protective as vaccination against severe illness and death, study finds,” employing a headline that didn’t look like it was trying to downplay any findings.

The article itself was written by Akshay Syal, M.D., and it mentioned a study published in The Lancet:

Immunity acquired from a Covid infection provides strong, lasting protection against the most severe outcomes of the illness, according to research published [February 16 2023] in The Lancet — protection, experts say, that’s on par with what’s provided through two doses of an mRNA vaccine.

Infection-acquired immunity cut the risk of hospitalization and death from a Covid reinfection by 88% for at least 10 months, the study found.

“This is really good news, in the sense that protection against severe disease and death after infection is really quite sustained at 10 months,” said the senior study author, Dr. Christopher Murray, the director of the Institute for Health Metrics and Evaluation at the University of Washington.


Still, experts stress that vaccination is the preferable route to immunity, given the risks of Covid, particularly in unvaccinated people.

On the same day, US News and World Report covered the publication and details of the research. The study itself was titled, “Past SARS-CoV-2 infection protection against re-infection: a systematic review and meta-analysis” and published in The Lancet on February 16 2023.

A summary included “Background” and “Methods,” the former articulating the purpose of the research with respect to public health policies:

Understanding the level and characteristics of protection from past SARS-CoV-2 infection against subsequent re-infection, symptomatic COVID-19 disease, and severe disease is essential for predicting future potential disease burden, for designing policies that restrict travel or access to venues where there is a high risk of transmission, and for informing choices about when to receive vaccine doses. We aimed to systematically synthesise studies to estimate protection from past infection by variant, and where data allow, by time since infection.

In this systematic review and meta-analysis, we identified, reviewed, and extracted from the scientific literature retrospective and prospective cohort studies and test-negative case-control studies published from inception up to Sept 31, 2022, that estimated the reduction in risk of COVID-19 among individuals with a past SARS-CoV-2 infection in comparison to those without a previous infection. We meta-analysed the effectiveness of past infection by outcome (infection, symptomatic disease, and severe disease), variant, and time since infection. We ran a Bayesian meta-regression to estimate the pooled estimates of protection. Risk-of-bias assessment was evaluated using the National Institutes of Health quality-assessment tools. The systematic review was PRISMA compliant and was registered with PROSPERO (number CRD42022303850).

After that, “Findings” and “Interpretation” appeared:

We identified a total of 65 studies from 19 different countries. Our meta-analyses showed that protection from past infection and any symptomatic disease was high for ancestral, alpha, beta, and delta variants, but was substantially lower for the omicron BA.1 variant. Pooled effectiveness against re-infection by the omicron BA.1 variant was 45·3% (95% uncertainty interval [UI] 17·3–76·1) and 44·0% (26·5–65·0) against omicron BA.1 symptomatic disease. Mean pooled effectiveness was greater than 78% against severe disease (hospitalisation and death) for all variants, including omicron BA.1. Protection from re-infection from ancestral, alpha, and delta variants declined over time but remained at 78·6% (49·8–93·6) at 40 weeks. Protection against re-infection by the omicron BA.1 variant declined more rapidly and was estimated at 36·1% (24·4–51·3) at 40 weeks. On the other hand, protection against severe disease remained high for all variants, with 90·2% (69·7–97·5) for ancestral, alpha, and delta variants, and 88·9% (84·7–90·9) for omicron BA.1 at 40 weeks.

Protection from past infection against re-infection from pre-omicron variants was very high and remained high even after 40 weeks. Protection was substantially lower for the omicron BA.1 variant and declined more rapidly over time than protection against previous variants. Protection from severe disease was high for all variants. The immunity conferred by past infection should be weighed alongside protection from vaccination when assessing future disease burden from COVID-19, providing guidance on when individuals should be vaccinated, and designing policies that mandate vaccination for workers or restrict access, on the basis of immune status, to settings where the risk of transmission is high, such as travel and high-occupancy indoor settings.

Maher correctly remembered the number “65” from the story, although he misinterpreted its context; “Findings” noted that researchers “identified a total of 65 studies from 19 different countries.” They added that their meta-analyses of the individuated studies indicated that “protection from past infection and any symptomatic disease was high for ancestral, alpha, beta, and delta variants, but was substantially lower for the omicron BA.1 variant.”

“Interpretation” concluded by stating that “immunity conferred by past infection should be weighed alongside protection from vaccination when assessing” a variety of factors associated with public health practices. Google News search results for “natural immunity” and “Lancet” included several links to Lancet articles on “hybrid immunity” from late November and early December 2022.

On February 17 2023, published “Fact Check: Did Study Find COVID Infection Just as Effective as Vaccine?”, citing a popular tweet about the NBC News article:’s fact check mentioned context that was, as usual, absent from social media discourse about the findings:

However, as the study added, while infection may be as effective (and perhaps more, by some measures) as the vaccine, there are other risks associated with infection-acquired immunity (such as “severe morbidity and mortality associated with the initial infection”).

The study added: “This balance of risk varies by the type of variant, with omicron for instance having less severe outcomes than delta, and other risk factors associated with the individual, such as age and other comorbidities.”

This is a crucial point that was not included as part of the commentary on Twitter; while infection may (at least according to this paper) provide a level of protection “by variant and over time… at least equivalent if not greater than that provided by two-dose mRNA vaccines,” the health risks from catching COVID without a vaccination remain.

Multiple studies have confirmed that the risk of death from COVID is far higher among those who remain unvaccinated compared to those who received the vaccine.


A popular February 2023 tweet quoted comedian Bill Maher on a “a giant study” from “65 countries,” which according to him deemed “natural immunity” to be “as good or better than the vaccine”; he went on to express skepticism that the news would be covered by the “liberal media.” The studyhe referenced was published on February 16 2023 in The Lancet, and it analyzed 65 studies from 19 countries, not studies from 65 countries. The meta-study was the subject of several news articles, and researchers concluded that “immunity conferred by past infection should be weighed alongside protection from vaccination when assessing future disease burden from COVID-19, providing guidance on when individuals should be vaccinated, and designing policies that mandate vaccination for workers.”

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