If infection rates are higher with age, would it be reasonable to expect that efficacy would also vary with age?
The CDC has a website called
Risk for COVID-19 Infection, Hospitalization, and Death By Age Group
that breaks down risk for cases (infection), hospitalization and death by age). I'm surprised that the rate compared to the reference group (aged 5-17) is 3x for people 18-29, but then stays 2x from ages 30 onward past 85 years of age.
Since people in their 80's are reasonably expected to have different life styles (e.g.: rates of employment, movement in society, isolation, nursing home placement), I would not have expected such a consistent finding. On the 2nd chart, the risks of hospitalization and death are far worse as people age.
Immune function may decline with age (hence why shingles, reactivation of latent viral infection from childhood, tends to occur late in life). But
Pfizer has a website with Phase 3 data stating
- "Efficacy was consistent across age, gender, race and ethnicity demographics; observed efficacy in adults over 65 years of age was over 94%"
Medscape 3-3-21 had an article (on the Pfizer vaccine, I believe):
BMI, Age, and Gender Affect COVID-19 Vaccine Antibody Response
- "The study involved 248 healthcare workers who each received two doses of the vaccine. Of the participants, 99.5% developed a humoral immune response after the second dose. Those responses varied by body mass index (BMI), age, and gender.
"The findings imply that female, lean and young people have an increased capacity to mount humoral immune responses compared to male, overweight and older populations," say Raul Pellini, professor at the IRCCS Regina Elena National Cancer Institute, Rome, Italy, and colleagues."
"In the Italian study, the participants ― 158 women and 90 men ― were assigned to receive a priming BNT162b2 vaccine dose with a booster at day 21. Blood and nasopharyngeal swabs were collected at baseline and 7 days after the second vaccine dose.
After the second dose, 99.5% of participants developed a humoral immune response; one person did not respond. None tested positive for SARS-CoV-2.
Titers of SARS-CoV-2 binding antibodies were greater in younger than in older participants. There were statistically significant differences between those aged 37 years and younger (453.5 AU/mL) in comparison with those aged 47 to 56 years (239.8 AU/mL;
P = .005), those aged 37 years and younger vs those older than 56 years (453.5 vs 182.4 AU/mL;
P < .0001), and those aged 37 to 47 years vs those older than 56 years (330.9 vs 182.4 AU/mL;
P = .01).
Antibody response was significantly greater for women than for men (338.5 vs 212.6 AU/mL;
P = .001).
Humoral responses were greater in persons of normal-weight BMI (18.5 to 24.9 kg/m2; 325.8 AU/mL) and those of underweight BMI (<18.5 kg/m2; 455.4 AU/mL) compared with persons with preobesity, defined as BMI of 25 to 29.9 kg/m2 (222.4 AU/mL), and those with obesity (BMI ≥30 kg/m2; 167.0 AU/mL;
P < .0001). This association remained after adjustment for age (
P = .003)."
There's more to immune resistance than antibody levels. Each of us varies across a range of variables (e.g.: age, sex, weight, fitness, co-morbid medical conditions). It's also important to be mindful vaccine protection covers more than the efficacy %. I've read that the % 'failure' isn't really failure. So if you get the Pfizer vaccine and you're in the 5% that catches COVID-19 anyway, you still benefit - you're much less likely to get hospitalized or die compared to an otherwise similar non-vaccinated person with COVID-19.
I don't have an age/efficacy graph for each vaccine, but maybe that info. will be of interest.
