Do You Really Need 2 Vaccine Doses if You Already Had Covid-19?
France is the first country to vaccinate people who previously had Covid-19 with only one dose
In many countries, the demand for Covid-19 vaccines greatly outweighs the supply. This has been especially apparent in Europe: Late purchasing, a slow rollout, and problems with distribution have caused the European vaccine campaign to undergo a very shaky start.
France has had an even more troubling vaccine rollout than some of its European neighbors. With a current ratio of 4.12 vaccines per 100 people, France is behind the EU’s average. It trails countries like Germany, Spain, and Italy, and it’s especially far behind its neighbor, the U.K.
The French rollout has been criticized by the media and has faced a growing loss of faith from its citizens. To begin with, the French public was less inclined and relatively skeptical toward the vaccines, but even those who wished to receive a vaccine have sometimes found centers closed because there weren’t enough available doses. Some experts referred to it as a “fiasco.”
France has been seeking a safe way to boost its vaccination campaign and allow more people to receive the vaccine as quickly as possible. This is, naturally, a goal shared by many nations. The U.K., for example, recently took controversial steps in order to make do with the vaccine doses it has. It allowed people to delay the second dose and mix vaccines on rare occasions, stoking debate and criticism from parts of the scientific community.
France has now found a different approach, and it is actually one that many experts agree with.
On February 12, the French Haute Autorité de Santé (High Authority of Health) released a statement announcing two changes in the local protocol.
- A person who previously tested positive for Covid-19 — whether with or without symptoms — will be considered “protected” for a period of between three to six months post-infection as opposed to three months in the original guidelines.
- Within the six-month timeframe, and preferably closer to six months after infection, those who were previously tested positive will now receive only one dose of the vaccine, acting as a booster.
There are two exceptions:
- People with proven immunosuppression will still be vaccinated with the two-dose regime within three months of infection.
- People who developed Covid-19 after receiving the first vaccine dose will receive a second dose but within three to six months of infection.
France is thus the first country in the world to vaccinate people who previously had Covid-19 with only one dose. This decision was based on several recent studies.
One study, which hasn’t yet been peer-reviewed, was conducted by researchers at the University of Maryland who tested antibodies in previously Covid-19-positive health care workers after one vaccine dose. They found a significant antibody response compared with those who were vaccinated without previously being diagnosed with Covid-19.
A second study done by researchers from New York’s Icahn School of Medicine at Mount Sinai, which has also not yet been peer-reviewed, found that among 41 people who previously had Covid-19 and were vaccinated with one dose, antibody levels were up to 10 times higher than those of 68 participants who were never infected and fully vaccinated. The researchers also found that people who were previously diagnosed with Covid-19 more frequently reported side effects after receiving the first dose, further indicating a more robust response.
A third study that was published recently examined 514 staff members at Ziv Hospital in northern Israel who received the first dose of a vaccine, 17 of whom were previously diagnosed with Covid-19. Among these 17 people, a very strong antibody response — nearly amounting to the “full protection” of two vaccine doses — was detected, even in those who were initially diagnosed 10 months prior.
The researchers behind all of the mentioned studies commented that further examination is needed, but all concluded that one dose of vaccine for those previously diagnosed with Covid-19 is enough.
In the case of France, this change of protocol might prove significant. Over 3.4 million people have been diagnosed with Covid-19 throughout the country, and in this time of need, switching to a one-dose regime six months after infection could prove vital in the larger national scheme.
“Prime-boost vaccines work by mimicking natural immunity”, Dr. Peter English, a consultant in communicable disease control, explained with regard to the preprints from the University of Maryland and Mount Sinai. “It is no surprise at all that the first dose of vaccine, when given to people whose immune system is already primed by natural infection, will have a booster effect very similar to the effect when given as a second, ‘booster’ dose.”
While the results seem promising on paper, there are potential complications to take into account. “Incorporating [a one-dose regime] into a mass vaccination program may be logistically complex”, said Eleanor Riley, PhD, from the University of Edinburgh about the preprints, noting, “It may be safer, overall, to ensure that everyone gets two doses.”
Indeed, the French High Health Authority did not elaborate on how the mechanism will work. It’s definitely more complicated than simply administrating two doses to everyone. And yet when the world, and France in particular, are in desperate need of vaccines, it’s worth trying everything possible — as long as it’s safe — to ensure as many people as possible are well protected.