Despite those studies, Pfizer announced on Oct. 7 that it had asked the Food and Drug Administration (FDA) to authorize their coronavirus vaccine for use on children five to 11 years old.
The researchers have examined data from 4,800 healthcare workers in a prospective longitudinal study in Israel. Their findings show that antibody levels waned rapidly after two doses of the Pfizer vaccine, particularly among men, adults aged 65 and older and in those with immunosuppression.
They have tested the antibodies of participants during the baseline period, defined as four to 17 days after receipt of a second vaccine dose, and every four weeks thereafter over a six-month period. The highest titers after getting their second vaccine dose were observed during days four to 30, defined as the peak period.
A titer refers to the measurement of the amount or concentration of a substance in a solution, like the amount of antibodies in your blood.
But since the scientists are unable to perform neutralizing antibody assays in all the volunteers, they select a subgroup of higher proportions of individuals with risk factors of interest, such as being 65 or older and having coexisting conditions.
They have found that levels of neutralizing antibodies, the immune system's first line of defense against infection, are linked to protection against infection. But for this study, the scientists have only analyzed antibody levels.
Additionally, the research team has observed a significant reduction in the immunoglobulin (IgG) level each month, along with a notable decrease in neutralizing antibody titers.
In many studies about various vaccines, like those against measles, mumps and rubella, there's a small decrease each year of five to 10 percent in the neutralizing antibody levels. The researchers conclude that there is "a significant and rapid decrease in humoral response" to the Pfizer vaccine months after inoculation.
A second study from Qatar has analyzed actual infections among the nation's population, which had a high rate of inoculation with Pfizer's coronavirus vaccine.
Data has shown that estimated effectiveness against coronavirus infection was insignificant for the first two weeks after the first Pfizer dose. Effectiveness was up to 36.8 percent in the third week after receiving the first dose, reaching its peak at 77.5 percent in the first month after getting the second dose.
Pfizer has often claimed that its own efficacy data demonstrated 95 percent efficacy against coronavirus during clinical trials, which wasn't the case in the Qatar study. Scientists say that its effectiveness declined gradually, starting from the first month after receiving the second dose.
Effectiveness then accelerated following the fourth month and reached a low level of an estimated 20 percent in months five through seven after getting the second dose.
"BNT162b2-induced protection against infection builds rapidly after the first dose, peaks in the first month after the second dose, and then gradually wanes in subsequent months. The waning appears to accelerate after the fourth month, to reach a low level of approximately 20 [percent] in subsequent months," write Laith Abu-Raddad of Weill Cornell Medicine-Qatar and colleagues, authors of the Qatar study.
In the study, which concluded on Sept. 5, researchers recorded a total of 8,203 coronavirus Pfizer breakthrough infections among the 947,035 volunteers who received one vaccine dose. There's also 10,543 breakthrough infections recorded in the 907,763 participants who received two doses of the vaccine.
The percentage of all daily breakthrough infections from both Pfizer and Moderna reached 36.4 percent on Sept. 5, with 77.2 percent of breakthrough infections linked to Pfizer's vaccine.
In a separate Pfizer-funded study published in the journal The Lancet, scientists have discovered that the efficacy of the Pfizer vaccine dropped below 50 percent six months after getting the second dose.
For the study, scientists have analyzed 3.4 million electronic records from the Kaiser Permanente Southern California (KPSC) healthcare system for patients aged 12 and older. The patients were monitored from December 2020 to August 2021.
Findings have shown that Pfizer's vaccine was 88 percent effective in the first month after full vaccination. However, effectiveness dropped to 47 percent effectiveness after six months or so.
The scientists have concluded that people who were fully vaccinated with two doses of the Pfizer vaccine had an overall 73 percent effective protection against coronavirus and 90 percent effective protection against coronavirus-related hospitalization.
On Oct. 7, Pfizer asked the FDA to authorize its COVID-19 vaccine for emergency use for young children aged five to 11 years old.
An FDA advisory committee is slated to meet on Oct. 26 to discuss the vaccine for children. Officials say its authorization could take place between Halloween and Thanksgiving later this year.
FDA officials explain that the agency could authorize a vaccine for younger children within weeks once following the submission of vaccine data. Pfizer has submitted initial data to the FDA last September for a regimen of two 10-microgram doses in children, which is one-third the amount given to older patients. (Related: Critics blasts FDA for full “approval” of Pfizer vaccine.)
Alex Berenson, former New York Times reporter and author, warns that Pfizer's clinical data of the vaccine showed no evidence of actual health benefit to the children who received it. He adds that in Pfizer's 2,300-patient child trial, data only showed that its mRNA doses can make kids produce spike proteins. The has vaccine also had adverse side effects.
Berenson says that based on Pfizer's Sept. 20 press release announcing the trial's results, the trial didn't show if the vaccine could reduce hospitalizations, which isn't that significant as cases are almost non-existent in healthy children.
Pfizer's press release doesn't indicate that the vaccine makes kids stay healthy. It also admits that the vaccine has side effects similar to those observed in participants aged 16 to 25, such as severe headaches, fatigue and fever.
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