The Virus Outbreak Thread

On Dec. 3, 2020, Pfizer’s CEO, Albert Bourla, told NBC News it was still unknown if vaccinated people could carry the virus and spread it to others. “I think this is something that needs to be examined. We are not certain about that right now,” he said.

Yet recent online posts claim, as if it were breaking news, that a Pfizer executive “admits” the vaccine was never tested for whether it prevented transmission. Social media posts claim the supposed “shocking admission” was “criminal” and “indisputable proof of the fact that our governments lied to us.”

The posts cite remarks by Pfizer’s president of international developed markets, Janine Small, while testifying on behalf of Bourla before the European Parliament’s COVID-19 committee on Oct. 10.

During the session, a conservative Dutch member of the Parliament, Rob Roos, asked Small if Pfizer had tested the vaccine for transmission prevention before the vaccine entered the market (see the 15:23:00 mark of the video). Small said: “No. We had to really move at the speed of science to really understand what is taking place in the market” (see the 15:31:45 mark).

Following the hearing, Roos posted a two-minute video statement on Twitter that included his exchange with Small.

“BREAKING: In COVID hearing, #Pfizer director admits: #vaccine was never tested on preventing transmission. ‘Get vaccinated for others’ was always a lie. The only purpose of the #COVID passport: forcing people to get vaccinated. The world needs to know. Share this video!” said the post, which got 232,600 likes and 138,500 shares in less than two days.

“I find this to be shocking, even criminal,” Roos said in his video statement.

But as we said, nobody claimed the vaccines — Pfizer’s nor Moderna’s — were tested for transmission prevention before they hit the market. Those studies started once the vaccines were being administered.

“Our landmark phase 3 clinical trial (protocol published November 2020) was designed and powered to evaluate efficacy of BNT165b2 to prevent disease caused by SARS-CoV2, including severe disease. Stopping transmission was not a study endpoint,” Pfizer’s global media relations senior director, Andrew Widger, told us in an email, referring to the company’s vaccine.

That’s not uncommon. In a commentary published in Science in March, Natalie E. Dean, assistant professor in the Department of Biostatistics & Bioinformatics at the Emory University Rollins School of Public Health, and M. Elizabeth Halloran, head of the Biostatistics, Bioinformatics and Epidemiology Program at the Fred Hutchinson Cancer Research Center’s Vaccine and Infectious Disease Division, wrote that estimating indirect effects of a vaccine, such as reduction in infectiousness, “is typically done after a vaccine is licensed, in either observational studies or cluster randomized trials.”

The primary benefit of an effective vaccine is to prevent symptomatic disease, Dean told us in an email, and “given the urgent need to prevent COVID-19 illness, the trials focused on these primary goals,” she said. A secondary benefit of an effective vaccine is to reduce transmission, she added, either by protecting against infection or by making infected people less contagious. “But assessing protection against infection requires specialized tests (antibody tests or more frequent sampling) and, to measure contagiousness, measuring viral load and, preferably, studying family members or other contacts,” she said.

We explained the difference between infection with a virus and disease, or the development of illness, in this video.

Roos did not reply to our request for comment, but he told the Associated Press that governments infringed on fundamental rights by imposing vaccine mandates with “no evidence” that the vaccines stopped transmission. In an appearance on Fox News’ “Tucker Carlson Tonight” on Oct. 11, he said that “governments pushed millions of people worldwide to get vaccinated by telling them … do it for your grandmother” and introduced “so-called COVID passports,” mandates and lockdowns “in the name of public health.”

“All of this was based on the idea that vaccination helps prevent the spread of the virus, otherwise, why shun people out of society? But this has now proven to be a big lie,” Roos said.

To be fair, some officials have overstated the transmission protection provided by the vaccines. But studies did find that vaccinated people were much less likely to spread the virus, either because they were protected from getting infected in the first place, or by being less contagious if infected.

As we’ve reported, that became less true with the emergence of the more transmissible and immune evasive omicron variant, but there is still evidence that for a short period, vaccines help reduce omicron transmission somewhat.

“Being up to date with vaccination provides a transient period of increased protection against infection and transmission after the most recent dose, although protection can wane over time,” CDC experts wrote in their latest guidance for minimizing the impact of COVID-19.

In their commentary, Dean and Halloran mention two studies published in Science based on data from Israel to argue that there are multiple factors that affect the ability of COVID-19 vaccines to reduce transmission, such as time since vaccination and evasive variants.

One of the studies found that in households with one infected parent, the chances of at least one unvaccinated child becoming infected were much lower if that parent was vaccinated. The chance of infection was 72.1% lower with a vaccinated parent during the alpha period, shortly after the vaccines were rolled out, and 79.6% lower during the delta period. The other study found that vaccines reduce infectiousness by 23% using data from before the emergence of delta.

“COVID-19 vaccines have provided exceptional protection against severe disease, and they have reduced transmission. Notably, indirect protection is not all or nothing but rather incrementally increases with each newly immunized person. Ensuring our communities are well vaccinated is a major priority as SARS-CoV-2 becomes endemic,” Dean and Halloran concluded.

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

“The problem of saying ‘I’m gonna get infected to get immunity’ is you might be one of those people that end up in the hospital or die,” Murray said. “Why would you take the risk when you can get immunity through vaccination quite safely?”