Catching covid between your first and second dose of vaccine is possible, and it is not uncommon. So much so that this phenomenon has a name: the “vaccinee syndrome” or “first dose syndrome”.

We have more and more of this type of patient in our departments. They see their first dose as a totem pole“thus confided on May 26 to Parisian Doctor Benjamin Davido, infectious disease specialist at Garches hospital.

Effective 15 days after the 2nd dose

However, the vaccine is not effective immediately, quite the contrary since vaccine protection is built up gradually, reaching its maximum 15 days after the second dose.

Thus, for the Pfizer and Moderna messenger RNA vaccines, protection against severe forms of covid is approximately 80% between 14 and 21 days after the first dose. It reaches almost 95% two weeks after the second dose.

For AstraZeneca, protection against severe forms is 70% one month after the first dose and almost 90% two weeks after the second.

Read also: Questions about the second injection of the Astrazeneca vaccine

Risk of variants

And in all cases, after the first or second dose, barrier gestures remain in place. On the one hand, because the protection conferred by vaccines is not 100%. And on the other hand, because the effectiveness of vaccines against the variants of the coronavirus which are currently circulating is still poorly understood.

The UK is a sad example. After a lull in the epidemic in the spring, the figures are now on the rise and nearly three quarters of new positive cases are due to the Indian variant.

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A (too) long period at risk

However, the latest scientific studies show that the Pfizer, Moderna and AstraZeneca vaccines are very effective against the Indian variant. Provided that both doses have been administered.

However, in the United Kingdom, nearly 60% of the population is vaccinated… but with only one dose. Full vaccination only affects 38% of Britons. And the two doses are all 12 weeks apart, regardless of the vaccine. This is a risk period twice as long as in France for messenger RNA vaccines, where it is now six weeks.