Vaccines

SARS-CoV-2 is a member of the genus β-coronavirus and subgenus sarbecovirus. Other sarbecoviruses have already caused epidemics, such as SARS-CoV in 2003 (about 8 000 infections and 800 deaths) and MERS-CoV in 2012 (at least 2 600 cases and 900 deaths). Sarbecoviruses have spike surface proteins, the target of powerful neutralising antibodies, that differ while […]

Obtaining a vaccine that works against COVID-19 has been one of the main priorities of recent times. Numerous candidate vaccines, using different technological platforms, have been developed. These vaccines, designed by expressing the SARS-CoV-2 spike surface protein, induce neutralising antibodies against this virus. However, the emergence of variants such as Alpha or Delta, that have […]

For several months, the emergence of new SARS-CoV-2 variants has been closely monitored since these new strains may be more virulent, and may evade immunity, even when it derives from vaccination. This is notably the case with the Alpha (⍺) (UK), Beta (β) (South African), Gamma (ɣ) (Brazilian), Epsilon (ε) (Californian), Delta (δ) (Indian) and […]

SARS-CoV-2 has infected more millions of  people. Brazil has been the most affected country with more than 15 million cases and more than 430 000 deaths. Vaccines have allowed us to greatly reduce mortality rates, and amongst available vaccines, the CoronaVac (also called Sinovac), developed in China, is the only one to use the traditional technology of […]

When a sufficiently large percentage of a population is immunised against a pathogen, this latter can no longer cause large-scale epidemics. Immunity may be acquired through vaccination, or natural infection. What are the practical issues involved in attaining it? In the absence of vaccination, and if immunity is long-lasting and has a sterilising effect (absence […]

Vaccines have been a vital part of eradicating or controlling several deadly infections diseases in the past. But reaching high enough levels of vaccination coverage to attain herd immunity is often a challenge. So, while several safe and effective vaccines against COVID-19 are currently available, some 30% of Americans are hesitant or reticent, as in […]

Since March 2021, India has suffered an explosion in cases of COVID-19, with more than 400 000 new infections and 4 000 deaths per day at the height of the crisis at the beginning of May. Genome sequencing of the virus uncovered a new strain, the Delta (B1.617 or Indian) variant which, since May, has been […]

By the end of June 2021, more than a dozen anti-COVID-19 vaccines had received authorisation in numerous countries. The AstraZeneca vaccine, for example, had received the largest number of authorisations, in 115 countries. The Pfizer-BioNTech vaccine had been approved in more than 90 countries. Distribution of vaccines has been unequal, with the majority of stocks […]

In order to give us protection in this pandemic, vaccines need to available as well as effective. At the current time there are many inequalities in vaccine access. More precisely, there are two types of discrepancies: Firstly, developed countries have obtained the majority of the world’s stock of vaccines, by buying up more than two […]

Thromboembolic events are a rare but serious side-effect of the AstraZeneca adenovirus vaccine. A clot forms, blocking a vein or an artery, and can cause a pulmonary embolism. Thromboembolic disease exists naturally (that is, not linked to the AstraZeneca vaccine) in the general population, with some 130 000 hospitalisations in France in 2014. Some risk factors […]