Two recent trials indicate that the immunological protection provided by two doses of Pfizer’s Covid-19 vaccine wears off after about two months, while protection against severe illness, hospitalization, and death remains robust.
The findings, which were published in the New England Journal of Medicine and come from Israel and Qatar, back up claims that even fully vaccinated persons should take measures against infection.
Antibody levels drop quickly after two doses of vaccination, according to an Israeli research that included 4,800 health care professionals. “Especially among men, individuals 65 years of age or older, and persons with immunosuppression,” the study found.
Dr. Gili Regev-Yochay of Sheba Medical Facility and colleagues stated, “We performed this prospective longitudinal cohort research including health care professionals at Sheba Medical Center, a prominent tertiary medical center in Israel.”
The researchers highlighted that levels of so-called neutralizing antibodies, which are the immune system’s initial line of defense against infection, are linked to infection protection, but they focused on antibody levels in this study.
“Published research on several vaccinations, such as those against measles, mumps, and rubella, has indicated a modest decline in neutralizing antibody levels each year of 5 to 10%,” they stated. “Within months of immunization, we detected a large and fast reduction in humoral response to the BNT162b2 vaccine.”
The study also found that those who are vaccinated after a natural Covid-19 infection have longer-lasting protection. It’s most potent in those who have recovered from illness and then been vaccinated. “Overall, data from our trial and others suggests that long-term humoral response and vaccination efficacy in previously infected people were superior to those in two-dose vaccine recipients,” they concluded.
A second research from Qatar looked at real illnesses in that small Gulf nation’s highly vaccinated populace. Pfizer/vaccination, BioNTech’s also known as BNT162b2, was given to the majority of those that went.
“BNT162b2-induced protection against infection increases quickly after the first dosage, peaks in the first month following the second dose, and then gradually fades in future months,” said Laith Abu-Raddad and colleagues from Weill Cornell Medicine-Qatar. “After the fourth month, the fading tends to increase, reaching a low of around 20% in succeeding months,” they noted.
Nonetheless, they reported that protection against hospitalization and mortality remained over 90%.
They speculated that the diminishing protection may be due to behavior. “Vaccinated people are likely to have more social interaction than unvaccinated people, and they may also adhere to less safety precautions,” they noted. “This behavior might lower the vaccine’s real-world efficacy relative to its biologic efficiency, which could explain why protection is fading.”
However, it is a warning that governments should prepare for further Covid-19 outbreaks. “These data imply that in the next months, a substantial part of the vaccinated population may lose protection against infection, thereby raising the risk of future epidemic waves,” they concluded.
Pfizer claims that after a few months, protection from the first two doses of their vaccine begins to run off. Pfizer received approval from the US Food and Drug Administration last month for booster doses of its vaccine for six months after individuals had completed their first two doses.
People over 65, people with conditions that make them more susceptible to becoming seriously ill from breakthrough infections, and people at high risk of infection, such as health care workers and prison inmates, should all get boosters, according to the US Centers for Disease Control and Prevention.
Israel has been increasing its population and has recently announced that people would need a third injection to be deemed completely immunized.
According to CDC data, more than 6 million people in the United States have gotten a third dose of vaccination, and the average rate of booster injections is greater than the rate of those becoming vaccinated for the first time.