Reader question: France is aiming to vaccinate 10 million people in April but why this number? Surely that amount is far too low to offer herd-immunity?
Prime Minister Jean Castex did indeed say on Saturday (March 13) that the country’s objective is to give a first dose of a Covid-19 vaccination to 10 million people by mid-April.
Objectif : 10 millions de vaccinations au 15 avril.— Jean Castex (@JeanCASTEX) March 13, 2021
Ici, à Saint-Maixent-l'École, et partout dans le pays, la mobilisation générale se poursuit et s'amplifie pour freiner le virus, nous protéger - et protéger ceux que nous aimons.
Notre engagement est total. pic.twitter.com/ac71qmbqGP
He said he was hopeful that the country would reach this goal, adding that it depended on deliveries of vaccine doses.
Since then, AstraZeneca has announced further delays to deliveries.
Then yesterday (March 15), President Emmanuel Macron announced that France was temporarily suspending the use of the AstraZeneca vaccine due to concerns over side effects.
A little over five million people in France have received a first dose of a Covid-19 vaccination, equal to 7.67% of the population.
Will vaccinating 10 million people lead to herd immunity?
The ultimate aim of the vaccination campaign is to inoculate enough people against the virus Sars-CoV-2 so that it stops circulating among the population. This is what is called herd immunity.
It has still not been confirmed if the various Covid-19 vaccines on the market prevent transmission of the virus. They have all been proven - to different degrees of efficiency - to reduce the risk of the Covid-19 disease developing in people once they have caught the virus.
A recent study carried out by Public Health Scotland and the University of Glasgow found that two doses of the Pfizer-BioNTech or AstraZeneca vaccine - both of which are approved for use in France - reduces transmission of the virus by at least 30%.
Even if the vaccines do reduce transmission, there are still other factors to consider when trying to calculate how many people will need to receive them before herd immunity is achieved.
This includes the length of times the vaccines will give immunity to people, the possibility of new variants, the number of people who have already had Covid-19, etc.
The general scientific consensus is that it will be necessary to vaccinate between 60 to 80% of people to achieve herd immunity. The number of 10 million people is far below that.
So why 10 million?
The number mentioned by Mr Castex corresponds approximately to the number of people who are most vulnerable to serious forms of Covid-19.
There are roughly 6.4 million over 75s in France, with age being the most important factor in determining who is at risk of Covid-19, France’s health authority the Haute Autorité de Santé states.
There are a further one million people younger than 75 who have serious health conditions that could result in severe cases of Covid-19.
If you add all the health workers who are regularly exposed to Covid-19 patients to the equation, you get a rough number of eight to nine million, Le Figaro reported.
This means that after 10 million first doses, the most vulnerable people in the country will be at least partially protected from serious forms of Covid-19 (two doses are required for full efficacy in all of the vaccines approved for use in France except for the Johnson & Johnson vaccine, which could be rolled out in April and requires only one dose).
This number then is crucial as with these people protected, the pressure on hospitals and intensive care units should decrease.
Currently, 81.9% of beds in intensive care wards in France - according to how many there were in 2018 - are occupied.
There are 4,219 people in intensive care units right now due to Covid-19, an increase of 10% from the previous week, as shown in the graph below.
If France is able to vaccinate the 10 million most vulnerable people by mid-April, it will be an important first step and it should lead to less pressure on hospitals by the beginning of May.
It is, though, still a long way from the government target of vaccinating every willing adult by the end of the summer.