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Causes of breakthrough infections include biological factors in the recipient, improper administration or storage of vaccines, mutations in viruses, blocking antibody formation, and other factors. For these reasons, vaccines are rarely 100% effective. A 2021 study found the common flu vaccine provided immunity to the flu in 58% of recipients. [6]
Therefore, HA is responsible for binding influenza viruses to sialic acid on the surface of target cells, such as cells in the upper respiratory tract or erythrocytes, [3] resulting in the internalization of the virus. [4] Additionally, HA is responsible for the fusion of the viral envelope with the late endosomal membrane once exposed to low ...
To produce viral vaccines, candidate vaccine viruses are grown in mammalian, avian or insect tissue culture of cells with a finite lifespan. [5] These cells are typically Madin-Darby Canine Kidney cells, [6] but others are also used including monkey cell lines pMK and Vero and human cell lines HEK 293, MRC 5, Per.C6, PMK, and WI-38. [7]
Of the 158 children who were eligible for the flu vaccine, 131 (or 83%) were not fully vaccinated, per the CDC. ... This is one of the worst annual flu death totals in children in a season ...
Viral neuraminidase cleaves terminal sialic acid residues from glycan structures on the surface of the infected cell. This promotes the release of progeny viruses and the spread of the virus from the host cell to uninfected surrounding cells. Neuraminidase also cleaves sialic acid residues from viral proteins, preventing aggregation of viruses.
The viruses can invade lung epithelial cells and alveolar macrophages to produce viral nucleic acid, which stimulates the infected cells to release cytokines and chemokines, activating macrophages, dendritic cells, and others. [5] Cytokine storm syndrome is a diverse set of conditions that can result in a cytokine storm.
However, the nasal spray vaccine won’t cause influenza illness. According to the FluMist package insert , the flu spray is about as effective as the shot: 45%, compared to between 40% and 60% ...
[1] [11] Antigenic drift occurs in all influenza species but is slower in B than A and slowest in C and D. [26] Antigenic drift is a major cause of seasonal influenza, [34] and requires that flu vaccines be updated annually. HA is the main component of inactivated vaccines, so surveillance monitors antigenic drift of this antigen among ...