Why Masks If Vaccinated?

A new study by the US Center for Disease Control (CDC, PDF of the study) looked at residents of a county in Massachusetts that includes Provincetown, a famous holiday destination with lots of opportunities for dancing and other means of having a "good time", including the exchange of body fluids. This is thus not exactly the general population and would be comparable to British or German drinking tourists on the Balearic island of Mallorca.

In July, about 469 of those residents were infected with SARS-CoV-2. Of these ¾ had been fully vaccinated and yet, 80% of them reported symptoms. The researchers concluded that a fully vaccinated person has a similar viral load as a non-vaccinated person. This, however, does not mean that the viruses given off a vaccinated person are as infectious as those given off an unvaccinated one. The CDC study was not set up to answer this question.

But it corroborates what we have learnt during the past months about vaccinated persons giving off viruses. The CDC has therefore reversed its ill-advised recommendation from last May to no longer require masks. In fact, it is highly likely that very few of the 469 residents wore masks when partying and thus, the CDC's earlier recommendation is directly responsible for these infections.

My take-home message from this study is very different: don't go partying until herd immunity is reached.

So why masks indoors? I found this very catchy description in the CNN article:

Aerosols containing Covid-19 can travel as easily as the smoke from a cigarette, Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said Friday.
"If you want to understand what an aerosol is, just think of somebody smoking," Osterholm told CNN. "If you can smell a cigarette in the location you're at, then you're breathing someone else's air that may have the virus in it."

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