The study in Annals of Internal Medicine looked at symptom reports and antibody responses from 363 recipients of the Pfizer-BioNTech or Moderna mRNA vaccines when they were introduced. After the second dose of the vaccine, the researchers found that those with seven or more symptoms had nearly double the antibody levels than those who did not have symptoms.
As for those who complained about feeling too warm, the study team determined that those whose skin temperature increased by 1º Celsius after the second dose had three times the antibody levels 6 months later, compared with those whose temperature did not increase. The finding was based on about 40% of study participants who wore a device to monitor their temperature, breathing, and heart rates.
“Generally, we found that the higher the number of side effects, the higher the level of antibodies,” explained first author Ethan Dutcher, MD, PhD, a postdoctoral researcher in the University of California, San Francisco (UCSF) Department of Psychiatry and Behavioral Sciences and the Weill Institute for Neurosciences. “But this wasn’t a hard rule: some people without side effects had better antibodies than some people with side effects.”
Concern about side effects is often offered as a reason for SARS-CoV-2 vaccine hesitancy. The UCSF-led prospective cohort study sought to determine whether short-term side effects of SARS-CoV-2 mRNA vaccination are associated with subsequent neutralizing antibody (nAb) response.
The study included 363 adults from the San Francisco Bay area who had not been vaccinated against or exposed to SARS-CoV-2. Most of the participants (65.6%) were female with a mean age of 52.4 years.
At 1 month and 6 months after the second vaccine dose, researchers measured the serum nAb titer; daily symptom surveys and objective biometric measurements were collected after each dose.
The results indicated that chills, tiredness, feeling unwell, and headache after the second dose were each associated with 1.4- to 1.6-fold higher nAb at 1 and 6 months after vaccination. “Symptom count and vaccination-induced change in skin temperature and heart rate were all positively associated with nAB across both follow-up time points,” according to the authors. “Each 1º C[elcius] increase in skin temperature after dose 2 was associated with 1.8-fold higher nAB 1 month later and 3.1-fold higher nAB 6 months later.”
The study team concludes that short-term systemic side effects of SARS-CoV-2 mRNA vaccination are associated with greater long-lasting nAB responses and suggest their findings could be relevant in addressing negative attitudes toward vaccine side effects, which are a barrier to vaccine uptake.
“The toll of COVID is still high for some—sickness, lost work, lasting fatigue and the dreaded long COVID,” said cosenior author Elissa Epel, PhD, a vice chair in the UCSF Department of Psychiatry and Behavioral Sciences. “While the symptoms from vaccination can be very unpleasant, it's important to remember that they don't come close to the disease's potential complications.”
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