According to a statement issued by the World Health Organization (WHO) in May 2021, the shelf life of a vaccine is a reflection of the time it retains its potency, stability and effectiveness, kept at a set temperature.
The expiration date does not affect the safety of the product, other than the amount of protection it provides because it decreases over time.
The text explains that if the vaccine has an expiration date of six months, if that period is met, the next day, the biological can still be used. “It is not that the date is automatically fulfilled, it loses all effectiveness, but that it is gradually decreasing.”
why some Vaccines expire sooner than others?
“All vaccines, for any disease, have an expiration date. The difference between them is in the platform of each one. There are some that last longer, others less. Everything depends on the stabilization of the product”, explained the pediatrician and vaccine expert Soraya Castro.
The specialist clarified that the vaccine Sinovac has an inactivated virus platform and the Pfizer It is called a messenger RNA-based vaccine. The vaccine AstraZeneca It is based on the spikes of the virus.
“Messenger RNA is simply that the genetic material is injected into the body, it enters the cells without modifying the virus, therefore, there can be no genetic abnormalities because it really is a synthetic material that has a single function, which is to order our body to make antibodies against that messenger RNA”, detailed the galena.
Castro specified that the messenger RNA immediately finishes fulfilling its function, vanishes and does not cause any risk to the organism.
Vaccines with messenger RNA have a stabilizer that is what allows them to be kept at a refrigeration temperature of 14 to 20 centigrade and they have a stabilizer that does not have a long shelf life, so their shelf life is short.
“At the end of the day, anyway, we have seen, because the evidence shows it, that after six months the antibodies begin to decline,” added the doctor.
Castro cited the example of the flu vaccine that lasts 12 months.
“It is a vaccine that has traditionally been given to pregnant women for years and it is known that it does not represent any problem.”
According to a publication of the Mayo Clinicmade in January 2022, the messenger RNA vaccine is genetically engineered to give your cells instructions on how to make the spike protein found on the surface of the COVID-19 virus.
After vaccination, the muscle cells begin to produce the protein parts of the spike and to place them on the surface of the cells. This causes the body to produce antibodies. If you later get infected with coronavirus, these antibodies will fight it off.
In the case of the vaccine AstraZeneca, the genetic material of the COVID-19 virus is put into a modified version of a different virus (viral vector). When the viral vector enters cells, it delivers the virus’s genetic material that instructs cells to make copies of the spike protein.
Once the cells show the spike proteins on the surface, the immune system responds and creates defense white blood cells and antibodies. If you later become infected with the Sars-Cov-2 virus, the antibodies will fight the virus.
Sinovac it is based on the spikes, but it is complete virion. That is, it works by injecting into the muscle a substance that contains a new coronavirus, SARS-CoV-2, which has been inactivated through physical and chemical processes.
The inactivated virus has lost the ability to induce the disease, but its ability to induce a specific immune response against COVID is preserved, not only against protein S, but also against other molecules present in this infectious agent.
According to statements by the Minister of Health, Daniel Riverathis form of attenuated virus is what allows vaccines Sinovac have a longer expiration date than vaccines Pfizer and AstraZeneca.
Rivera specified that the vaccines Sinovac available in the country expire in 2023, while the others every six months.
