The seasonal influenza (“flu”) vaccine is recommended for all people ≥ 6 months old who don’t have a contraindication (including pregnant women regardless of trimester) and is typically administered from late October through April in the United States.
The vaccine is manufactured in one of three ways:
- Egg-based (most common): a candidate virus vaccine (CVV) replicates within hen eggs. The resulting fluid is used to produce either inactivated flu vaccines (the killed virus’ antigens are concentrated and purified) or live, attenuated vaccines (the weakened virus is given as a nasal spray and not used in immunocompromised or pregnant patients).
- Cell-based: a CVV is replicated within mammalian cells with subsequent inactivation of the virus
- Recombinant: Ever hear of serotypes like “H5N1” or “H1N1?” The ‘H’ refers to hemagglutinin (HA) and ‘N’ refers to neuraminidase (NA) which allow the virus to attach and release from the host cell, respectively. The numbers refer to the subtype of that particular protein. A flu strain’s HA DNA is combined with an arthropod baculovirus vector to infect specified host cells. Within these cells, HA production is ramped up. The resulting protein is collected and purified as an inactivated vaccine for patients ≥ 18 years old.
So what about the adverse effects? Transient soreness in the site of injection, nasal congestion, and a fever are fairly common and do NOT mean “you got the flu.” Guillain-Barré syndrome (GBS) – an autoimmune attack of one’s peripheral nervous system – occurs in about 1-2 out of every MILLION vaccinated patients.
Trust in science and not the unsubstantiated hysteria created by anti-vaxxers who haven’t seen otherwise healthy, young patients who may have benefitted from vaccination end up on ECMO or even DIE. Get your flu vaccine!
Sources: CDC website and Influenza Vaccine for 2019-2020. (2020). JAMA, 323(1), 84. https://doi.org/10.1001/jama.2019.18016