Vaccines

Current vaccines, notably the Janssen vaccine, and the Moderna and Pfizer-BioNTech vaccines which use mRNA technology, are effective in the prevention of symptomatic COVID-19. These vaccines also reduce infection by the SARS-CoV-2 virus. In common with other countries, the United States began its vaccination campaign at the end of 2020. But over time, and because […]

There are a number of different anti-COVID-19 vaccines currently available. Rare but serious side effects have been reported for the AstraZeneca (AZ) vaccine. Several countries have therefore decided to administer the Pfizer-BioNTech (PB) vaccine to people younger than 55 who have already had a 1st dose of AZ. Previous clinical studies have analysed the efficacy […]

The reasons for the continuation of the pandemic include insufficient vaccination coverage, the weakening of antibody protection over time, and the emergence of variants of concern (VOCs) that are more resistant and that have increased transmissibility. Moderna has recently produced a vaccine (mRNA-1273.β)  “tweaked” to adapt to the Beta (South African) variant, one of the […]

The link between a strong neutralising antibody response and protection against infection by the virus has been clearly demonstrated. This is why more than 6 billion doses of the vaccine have been given in an attempt to control the pandemic. But the vaccines have been developed from the spike protein of the original Wuhan strain, […]

Attaining herd immunity, whether by infection or by vaccination, is necessary to control the pandemic while SARS-CoV-2 continues to circulate. Different vaccines have been available for several months now, notably the mRNA vaccines. These vaccines encode the spike surface protein of the original Wuhan strain and have been widely administered throughout the world. They are […]

In December 2020, the UK changed its vaccine administration regime for Pfizer-BioNTech and Astrazeneca by spacing the injections at more than 12 weeks instead of the usual 4. The intention was to accelerate vaccine coverage in the population with a single dose, so as to limit the incidence of severe cases of COVID-19. This policy […]

The aim of vaccines is to prevent death or invalidity caused by a pathogenic agent. Their development is long and difficult, in the main because they must be able to be given safely to people in good health. This is why vaccines do not exist against the majority of diseases. However, though it takes on […]

Safe and effective vaccines to protect against serious forms of COVID-19 are now available. But slow up-take and low levels of vaccine coverage are dangerous for public health. Developed countries are struggling to achieve more than 70% coverage of the population vaccinated. Some governments have put financial incentive schemes in place to encourage individuals to […]

Infection by SARS-CoV-2 produces B cell responses that express powerful antibodies against the virus. The B cells evolve for at least a year after infection. During this evolution, the effectiveness of the antibodies produced increases, making them notably more potent against emerging variants. Vaccination is different from natural infection (path of virus administration, nature and […]

The Johnson & Johnson vaccine is an adenovirus vectored vaccine expressing the spike protein of the Wuhan ancestral strain. It has 85% efficacy against severe forms of the disease and is administered in a single dose. It is helpful for countries with difficulties accessing vaccines. However, while we know that a supplementary dose of an […]