No Reason to Panic Over the Pfizer/South Africa Variant Study

Over the weekend, a new study involving the Pfizer/BioNTech covid-19 vaccine set off a wave of alarming—and at times misleading—headlines. The study, based on real-world data from Israel, found that the vaccine wasn’t as effective against B.1351, the variant first found in South Africa, as it was against other strains. However, as the study authors themselves point out, high vaccination rates and other precautions can still easily contain the spread of worrying variants like B.1351.

The research was released last Friday on the pre-print website medRxiv, led by researchers from Tel Aviv University in Israel. The authors conducted what’s known as a case-control study, which is when two or more groups of people in a real-world setting are studied and compared to one another. In this case, they looked at people who were given the Pfizer vaccine and compared them to unvaccinated people, using insurance claims data. They focused on whether vaccinated people were more likely to develop covid-19 from B.1351, also known as the South Africa variant, or B.1.1.7, another variant of the virus first found in the UK last year. Both variants are worrying because they’re more transmissible than earlier strains of the virus, while B.1351 in particular may be better at evading the immunity provided by our current vaccines.

As expected, the chances of infection in fully vaccinated people were drastically low, but not zero, compared to unvaccinated people. In partially and fully vaccinated people, these breakthrough infections were most often caused by B.1.1.7, the UK variant, suggesting that it’s become the primary version of the virus in the country. Overall, the incidence of the South Africa variant was rare, accounting for only 1% of positive cases found in the study, out of nearly 400 people who contracted covid-19. But in people fully vaccinated, cases of B.1351 became more common (but again, still quite rare).

“We found a disproportionately higher rate of the South African variant among people vaccinated with a second dose, compared to the unvaccinated group. This means that the South African variant is able, to some extent, to break through the vaccine’s protection,” study author Adi Stern told Reuters on Sunday.

The results line up with the lab data scientists have collected so far, indicating that our vaccines provide roughly as much protection against B.1.1.7 as they did against earlier strains and slightly less protection against B.1351. But crucially, this protection is still very good. In the new study, the team found no cases of B.1351 in people two or more weeks after their second vaccine dose. Cases, deaths, and hospitalizations related to covid-19 have shrunk dramatically in the country as more and more residents have gotten vaccinated (as of Sunday, 53% are fully vaccinated). So, clearly, the South Africa variant is not spreading widely there.

Many media outlets highlighted the supposedly dire implications of this research, while the Drudge Report went as far as to falsely blare: “Pfizer Can’t Stop SAFRICA Strain”. But the researchers are more optimistic about their own findings than the coverage suggests.

“To summarize: we see evidence for reduced vaccine effectiveness against the British variant, but after two doses—extremely high effectiveness kicks in. We see evidence for reduced vaccine effectiveness against the S.A. variant, but it does not spread in Israel,” Stern wrote on Twitter on Saturday.

And rather than spelling doom for vaccinating our way out of this pandemic, the findings should only encourage us to speed up the process.

“We think that this reduced effectiveness occurs only in a short window of time (no B.1.351 cases 14+ days post 2nd dose), and that the S.A. variant does not spread efficiently. Thus, even more of a reason to get vaccinated and drive down cases to zero!” Stern added.

In the U.S., there’s no indication that B.1.351 is poised to overtake the country. Much like in Israel, the bulk of new cases identified daily are linked to the B.1.1.7 UK variant. And while cases and hospitalizations do remain relatively high, deaths have once again started to decline, thanks largely to a successful vaccine rollout among high risk groups like the elderly. By the end of the week, it’s expected that over half the country’s population over 18 will be at least partially vaccinated.

Nor is B.1351 some unstoppable hulk. In South Africa, covid-19 cases have similarly plummeted in recent weeks. This drop is happening despite a limited vaccine rollout so far, but it might be partially attributed to ongoing public health measures to limit spread.

Ideally, the U.S. would be coupling its vaccination campaign with some of these same efforts to contain the pandemic, much as Israel did during its early rollout. Many experts have at least called for a pause in lifting restrictions on physical distancing and indoor businesses until the pandemic is clearly curtailed. But even so, the U.S still appears to be on track to soon reach the success that’s now become apparent in Israel, variants or not.