Why older people are harder to vaccinate

In a hypothetical alternative universe where we already have a vaccine against Covid-19, world leaders will have a choice about how to deliver it to the population. The most vulnerable people, along with the nurses, doctors and care workers who look after them, are likely to be protected first.

If only it were that straightforward. The most vulnerable age group, the elderly, are particularly tricky to vaccinate.

“We have very few vaccines designed for older populations,” says Shayan Sharif, a professor of vaccinology at the University of Guelph, Canada. “More often than not in the last century, most vaccines have targeted childhood diseases.”

Shingles is one exception, usually given to patients in their 70s, and there are one or two other vaccines for diseases like meningitis or human papillomavirus developed for young adults. But otherwise immunology is skewed in favour of children.

“We have a tremendous amount of knowledge about childhood diseases,” says Sharif. “When it comes to young adults, middle age and old age, we don’t have a lot of experience.”