What are the limitations of the flu vaccine?

However, current influenza vaccines have several limitations. Relatively long production times, limited vaccine capacity, moderate efficacy in certain populations and lack of cross-reactivity are important issues that need to be addressed.

Which subtypes of influenza have a vaccine?

Trivalent inactivated vaccine. The most widely used seasonal influenza vaccine is the trivalent inactivated vaccine (TIV). The conventional vaccine is composed of the 3 currently circulating seasonal influenza virus strains: two influenza A virus types (H3N2 and H1N1) and a B type.

What viruses will the 2020 2021 flu vaccines protect against?

The committee recommended that the quadrivalent formulation of egg-based influenza vaccines for the U.S. 2021-2022 influenza season contain the following: an A/Victoria/2570/2019 (H1N1) pdm09-like virus; an A/Cambodia/e0826360/2020 (H3N2)-like virus; a B/Washington/02/2019- like virus (B/Victoria lineage);

How many variants of influenza are included in each vaccine?

Flu shots are vaccines given with a needle, usually in the arm. Quadrivalent flu vaccines protect against four different flu viruses.

Why is it difficult to make vaccines for influenza?

In some years certain influenza viruses may not circulate until later in the influenza season, making it difficult to prepare a candidate vaccine virus in time for vaccine production. This can make vaccine virus selection very challenging.

What is the main problem in the use of the influenza vaccine?

But the difficulty with influenza vaccines is that the yield of human influenza viruses on tissue culture is much lower than in embryonated eggs. A new high-yield donor is needed for construction of recombinants with a new pandemic strain, which can replicate in a stable cell line with high titre.

How many subtypes of influenza are there?

Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively).

Why is it challenging to choose influenza strains to include in vaccines?

Today, the majority of influenza vaccines are still grown in chicken eggs. Some influenza viruses, like influenza A(H3N2) viruses, grow poorly in eggs, making it challenging to obtain good candidate vaccine viruses at times.

When was the influenza vaccine created?

Vaccination against influenza began in the 1930s, with large-scale availability in the United States beginning in 1945. It is on the World Health Organization’s List of Essential Medicines.

Is adenovirus a flu shot?

Adenovirus-based influenza vaccine Such vaccines have the potential to provide full protection from influenza infection by inhibiting viral replication.