Covid-19: what we learned from six months of vaccination

Medical staff prepare to vaccinate against Covid-19 with a dose of Covishield, the version of AstraZeneca by the Serum Institute of India, in Calcutta on June 9, 2021. AP - Bikas Das

Text by: Simon Rozé Follow

4 min

It has been six months since the vaccination against Covid-19 began.

Since then, 1.7 billion doses have been administered. 


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On December 8, 2020, 90-year-old Briton Margaret Keenan became the first person to receive a first dose of the vaccine as part of a mass vaccination campaign. Six months after this first injection, 1.7 billion doses have been injected around the world. The



takes the opportunity to draw an initial assessment. Above all, it retains the kept promise of efficiency.

An observation shared by Elisabeth Bouvet, president of the technical committee for vaccinations at the High Authority for Health (HAS):

Vaccines were mainly evaluated in terms of efficacy in severe forms

,” she explains.

It is absolutely remarkable: all countries can show illustrative figures. In France, the latest data show us a reduction of almost 90% in hospitalizations and deaths among vaccinated people aged 75.


Better still, this good behavior is maintained despite the emergence of variants, in particular from messenger RNA vaccines:


Despite a very small reduction, they generally retain the same efficacy in preventing the serious forms induced by the latest variants,"

confirms Elisabeth. Bouvet.

The effect remains very clear


The obligation does not work

However, effective as they are, it is not the vaccines that save lives, but the vaccination. Will this be sufficient to achieve population immunity and end the pandemic? We are still far from it: we can see that in several countries well advanced in their campaigns that they are marking time. In the United States, for example, after a very sustained pace for weeks, the momentum stalled when only 50% of adults received at least one dose. Could it be because all the people who want to be vaccinated have been or are in the process of being vaccinated? Would only the less convinced, even reluctant, remain?


Proceedings of the American Academy of Sciences (Pnas)

echo a German study in which researchers tried to determine what could be the means to convince the greatest number. First lesson: the obligation does not work, it only reinforces opposition to vaccination. The authors show, however, that a reluctance to vaccination is not necessarily set in stone. Opinions evolve, especially through mimicry and conformism. They note that the greater the number of vaccinated, the fewer refractories there are. The researchers insist, however, that this only works if the public authorities trust the population by providing them with reliable and transparent information.

 Read also: Covid-19: is a third dose of vaccine really essential?

Will summer have an impact?

As summer returns to the northern hemisphere, will sunny days have an effect on epidemic dynamics?

The World Meteorological Organization has set up a special research team dedicated to this question.

She provides several answers in her

first report


In short: we should not bet everything on it.

True, most respiratory viral infections have a seasonal cycle, with peaks during fall and winter, but epidemic waves of Covid-19 have been observed during warm seasons in warm regions.

The authors show that it is mainly individual behavior as well as the health measures taken by governments that have had an effect on the dynamics of the pandemic.

However, they do not exclude that in the future the Covid-19 will indeed become seasonal.

If this happens, then it will be possible to model and predict, to some extent, the magnitude of epidemic waves using meteorological data.

To read also: Anti-Covid-19 vaccines: the lifting of patents under debate in the European Parliament


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  • Coronavirus

  • Vaccines

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