COVID-19. What is “reactive” vaccination, this new strategy in the face of

While the epidemiological indicators are green and spreading virus Getting weaker and weaker in France, the Haute Autorité de santé (HAS) calls on the public authorities, Health And citizens must remain vigilant in the face of the spread of new, more contagious variants, particularly the delta variant (known as the Indian).

at latest notice, recommends the implementation of a “reactive” vaccine strategy, already in trial, as well as a “test-alert-protect” strategy. What is the point of vaccinating the relatives of a person who is already positive knowing that their immunization requires two doses of the vaccine … and thus several weeks?

#communication | #covid19 In the face of emerging variables, HAS recommends cross-pollination (currently in testing)
? Quickly vaccinate all companions (home, workplace, school, etc.) of the person with the variant

https://t.co/8kgpTp1Zne pic.twitter.com/vSGAQJxPhF

– Haute Autorité de santé (HAS_sante) June 21, 2021

The end of the “loop” strategy

So far, Haute Autorité de santé has called for vaccination “in the rings”. This strategy depends on the vaccination of contacts (1 .).^{he is} 1st generation ringing or dialing) plus contacts contacts (2^e episode) of a confirmed positive Covid-19 case. It was used to contain other epidemics such as Ebola.

For this device to be theoretically effective, several conditions must be taken into account, such as a delay in the incubation rate and virus infection, as well as a delay in the onset of protective immunity once the first dose is injected.

Delta variant, more contagious than others

In the face of the emergence of new variants such as the delta variant, HAS finally recommends switching to a reactive strategy. Reason ? The infection rate is much higher than “original breed” from Covid-19. In fact, the delta variant is estimated to be 60% more infectious than the alpha variant (known in English) and today accounts for 10% of pollution in France.

The increase in infections calls into question the efficacy of the “loop” vaccine strategy, which is too slow to contain worrisome variables. Furthermore it, “The loop vaccination strategy appears irrelevant due to the short incubation period for Covid-19 (average 5 days) and vaccine prophylaxis starting approximately 12 days after the vaccine is injected.”, explains HAS.

Vaccinate quickly and widely

Interactive vaccination aims to vaccinate “very quickly” And it is largely about a person who is positive for a variable of concern, once the latter is determined by sequencing.

In his last book Press release Posted on June 21, HAS explains that this device is about “All individuals in the household that were disclosed, people in their workplace, school or university.”.

In other words, it consists of fortifying an entire neighborhood or even an entire university in the event of a mass emergence. The goal is to break chains of transmission and avoid second generation contaminations.

Strong coordination between different actors

One of the conditions for the success of this strategy is “Optimal acceptance of vaccination by the population concerned.”

For this, it is necessary to increase contact between various public services, associations and vaccination sites in order to organize campaigns as quickly as possible and to overcome some operational limitations. Many fruitful experiments have already been carried out, as in the area Bacalan in Bordeaux or recently Kennedy slab in Viljan (Ren).

break transmission chain

Let’s take an example. Antoine organizes a party at his house and decides to invite two of his student friends: Jane and Clara. He learned a week later that he tested positive for Covid-19. It is rare for us to know that we are positive for the virus on the same day of infection. People tend to get tested after the first symptoms appear, 2-3 days after the peak of infection.

If we follow the strategy of reactive vaccination, then each class of Antoine, Jane and Clara will therefore be vaccinated directly, as soon as Antoine knows that he is positive. Students will be partially immune (up to 30%) after 12 days.

Unfortunately, Jane learned that she had contracted the virus in the meantime. The same for Clara. Just two days before finding out, on the D+11 day after the vaccination, Clara goes to a restaurant with Lucy, a student in her class.

Thanks to the “reactive” vaccination, Clara’s chain of transmission is likely to be halted because she is partially immune thanks to the first dose of vaccination along with the rest of her companions. If she is not vaccinated, she is likely to have contracted the virus and passed it on to other people.

Therefore, the “reactive” vaccine strategy makes it possible to slow the spread from the first cycle. The first dose is not enough and it is important to follow the full vaccination schedule, but it is not superfluous.

Vaccination with messenger RNA

Haute Autorité de santé advocates a preference for the use of RNA vaccines. why ? Pfizer-BioNtech and Moderna offer better efficacy on the first dose as well as early vaccine protection (after twelve days 30%) than AstraZeneca and Janssen.

For people who have already received their first dose, HAS recommends injecting messenger RNA into the second dose, trying to respect the recommended vaccination schedule.