Protection against infection offered by fourth Covid-19 vaccine dose wanes quickly...

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2. Article says the study wasn't long enough to to determine how long illness protection lasts.

Quote from the article:

However, protection against severe illness did not seem to wane in the six weeks after the fourth shot, though the study period wasn’t long enough to determine exactly how long this protection lasts.

The rate of confirmed infection in the fourth week after the fourth dose was lower than in the three-dose group by a factor of 2. There seemed to be maximum protection against Omicron in the fourth week after vaccination, but the rate ratio fell to 1.1 by the eighth week, suggesting that “protection against confirmed infection wanes quickly,” the study says.

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We need to distinguish between infection and illness.