The surprising vaccine side effects that may improve long-term health

I am currently planning to get a shingles vaccination. I had shingles at university and still have the scars so I really don’t want to risk getting it again. But I also keep in mind that the benefits of the shingles vaccine are not limited to preventing shingles. And this is not unusual. We’re discovering that many vaccines have benefits that go far beyond protecting against a single virus or bacteria—facts that aren’t nearly as widely known as they should be.

Let’s start with shingles. A study of more than a million people last year reported that those who received the Zostavax shingles vaccine were 26 percent less likely to die of heart disease or experience a stroke, heart attack or heart failure an average of six years after the shot — a massive reduction in risk for such a simple, cheap and easy intervention.

Also, people who received a newer shingles vaccine called Shingrix were 17 percent less likely to develop dementia over the next six years compared to those who received Zostavax. Since several studies have shown that Zostavax also reduces the risk of dementia, the overall risk reduction with Shingrix should be even greater. Several other vaccines, including those that protect against influenza and tuberculosis, also appear to reduce the risk of dementia.

In the US and Australia, shingles vaccination is recommended for those over 50 or adults with weakened immune systems. Unless you fall into the latter category in the UK it is only available through the public health system for those aged 70 to 79. I don’t want to wait that long so I will have to go private.

Shingles is caused by the varicella zoster virus, which causes chickenpox when it first infects us in childhood and then lies dormant in nerve cells, causing shingles when it reactivates. So it’s possible that vaccinating children against chickenpox will have some benefits later in life, although I couldn’t find any studies looking at this.

Influenza vaccines also have cardiovascular benefits. For example, an analysis that combined data from more than 9,000 people involved in six studies found that those vaccinated against the flu had a 34 percent lower risk of heart attack or stroke in the following year. The benefit was even greater for people with a recent history of heart problems.

The new vaccines for respiratory syncytial virus, or RSV, appear to help prevent heart problems as well. A study involving about 130,000 people over 60 found that those who had some kind of RSV vaccine were less likely to be hospitalized with heart or lung problems than those who were not vaccinated.

Then there are the covid-19 mRNA vaccines. They are shown to increase the immune response against tumors in connection with immunotherapy, and prolong people’s lives.

I could go on listing examples, but instead let’s look at why so many vaccines have these broader benefits. We don’t know the exact mechanisms for sure, but it’s not too surprising that they do.

Viruses can do permanent physical damage to the body, and the immune response to them can also damage tissue. So-called cytokine storms, where the body overreacts and releases too many immune-stimulating signals, is often what kills people with infections such as influenza or covid-19, and there is growing evidence that multiple sclerosis is a result of the immune response to the Epstein-Barr virus.

Many viruses also target our immune system in different ways to avoid it, weakening our defenses. HIV takes this strategy to the extreme, killing it completely.

There are also viruses that we cannot get rid of once they have infected us, for example the varicella zoster virus. Some, such as human papillomavirus (HPV), genetically modify our cells by inserting their genome into ours – this is why HPV causes cancer.

The point is that even viral infections that we tend to regard as harmless, such as the flu in young people, can have long-lasting effects that are not always obviously linked to these infections. Studies of long-term covid have helped raise awareness of this – and of the benefits of vaccines to reduce the risk of long-term damage.

There is this idea in some circles that “natural immunity” to getting a disease is somehow better than vaccination. It’s bonkers for all the reasons above and more, and measles is a prime example of why.

Measles vaccines have cut the number of deaths from the disease from more than 2 million a year before 1980 to fewer than 100,000 in 2024. They have also had the unexpected effect of reducing the number of children who die from other infectious diseases.

Why? Part of the answer is that measles kills some immune cells, making children more vulnerable to a wide range of infections for years afterwards. But measles vaccines also appear to train the immune system in a way that increases its broader effectiveness. This training effect is so beneficial that it has even been suggested that we should continue giving children the measles vaccine even after measles has been eliminated.

Of course, it would be too good to be true if all vaccines trained our immune systems in this way. There is evidence that a few vaccines have the opposite effect. But this doesn’t mean they don’t still save lives overall.

As always with vaccines, the key question is whether vaccinating is better than not vaccinating. To make an informed choice, you need to balance the risk of infection versus vaccination, also taking into account the wider benefits of a vaccine. Too often, the focus is exclusively on very rare or completely imaginary side effects of vaccines.

I have no doubts about what will make me better. I will get the shingles vaccine, and a flu shot every year, and the RSV vaccine when offered, at least.