We may not all be equal when it comes to vaccination, it seems. A team of researchers in the US reports that COVID-19 vaccines could be less effective in those suffering the most from stress, and whose immune systems may be weakened. The researchers suggest targeting these individuals with interventions to help improve their immune response to the vaccine.

Previous studies, spanning several decades, have documented how stress, depression and poor health behaviors can weaken the body's immune response to certain vaccines. This could potentially include the new vaccines developed in response to the COVID-19 pandemic, the first doses of which are now being administered to people in many countries worldwide.

However, we may not all get the same benefits from this vaccination, according to a report published in Perspectives on Psychological Science. Its authors explain that certain environmental factors, as well as the physical and mental health of an individual, could weaken the immune system and slow its response to the vaccine. The observation is particularly significant at a time when people around the world are experiencing trying times with successive lockdowns, restrictions and the many uncertainties brought about by the pandemic.

"In addition to the physical toll of COVID-19, the pandemic has an equally troubling mental health component, causing anxiety and depression, among many other related problems. Emotional stressors like these can affect a person's immune system, impairing their ability to ward off infections," said Annelise Madison, a researcher at The Ohio State University and lead author on the paper.

Short-term solutions can be effective

However, the researchers have good news too, reiterating that the currently available covid-19 vaccines are around 95% effective, and that these psychological and behavioral factors -- which could increase the time it takes to develop immunity and shorten the duration of immunity -- are modifiable in the short term.

According to the scientists, certain simple steps, like taking vigorous exercise and getting a good night's sleep in the 24 hours before vaccination, could help boost the immune system.

"Prior research suggests that psychological and behavioral interventions can improve vaccine responsiveness. Even shorter-term interventions can be effective," concludes Annelise Madison. "Therefore, now is the time to identify those at risk for a poor immune response and intervene on these risk factors."