Vaccine and transmission: An update

The biggest lingering question of the pandemic

The biggest, lingering question of the pandemic is: Does the COVID19 vaccine reduce transmission? Not all vaccines do, so this is important to figure out so we know what we can and cannot do (like stop wearing masks or visit non-vaccinated people).

Yesterday, two studies came out of Israel. A lot will start coming out from this country because 32% of their population is full vaccinated. This is the first place where we have “real world” data (opposed to a nicely controlled randomized clinical trial), so we can learn a LOT.

The first wasn’t really a study (by my standards) but a leaked report prepared by Israel's Health Ministry and Pfizer. I have yet to see this “leaked report” (I don’t have connections in this area), but Reuters got a copy. This is what they reported:

  • The study used a national database of the health records of hundreds of thousands of Israelis

  • The Pfizer vaccine reduced asymptomatic infection (i.e. transmission) by 89.4%

So far, Pfizer and Israel’s Health Ministry have “no comment”. But if this is confirmed, this is massive news (thus, why it was probably leaked). This will likely be the “ah ha” study we have all been waiting for. But, before we get excited, we really have to wait until other scientists (with no conflicts of interest) assess the rigor of the findings and point out any biases or mistakes. There is incredible value in peer-reviewed science.

The second study was published in the Lancet (and, thus, peer-reviewed). This study isn’t as exciting, though, because it’s a study within a study. In other words, the scientists didn’t intend to study transmission, so the sample is small and there are some limitations to the data. Nonetheless, this is what the scientists found:

  • The study was based in Israel’s Sheba Medical Center where they are following 7,214 hospital staff who received their first Pfizer dose in January

  • There was an 75% reduction in asymptomatic COVID-19 cases detected by testing

We can add both of these to our growing list that I will entitle: Glimmers of Reduced Transmission Hope. If you’re counting, there are now 4 sub-studies and 1 leaked report. All have found that the vaccine reduces transmission by ~60-80%. The other three sub-studies are:

  1. Moderna FDA report: 38 people in the placebo group had asymptomatic infection while 14 in the vaccine group had asymptomatic infection.

  2. Moderna tested 34 people for neutralizing antibodies over time. 119 days after the vaccine, everyone still had these antibodies.

  3. AstraZeneca study, which I talked about HERE

Love, YLE