Drinking alcohol after getting a coronavirus vaccine can significantly blunt the immune response and potentially render the vaccine ineffective, according to a leading Russian scientist. “We strongly recommend refraining from alcohol for three days after each injection,” Alexander Gintsburg, head of the Gamaleya National Center of Epidemiology and Microbiology in Moscow, which is developing the Sputnik V vaccine, told New Scientist.

This warning doesn’t just apply to the Sputnik V vaccine, but all covid-19 vaccines and indeed all other vaccines. “This is quite obvious,” he said.

Existing scientific literature on alcohol and the immune system shows that excess alcohol is an immunosuppressant so people who drink a lot are more susceptible to infections. “Heavy drinkers have many problems and poor immune function is one of them,” says immunologist Eleanor Riley at the University of Edinburgh, UK.

In trials, about 10 per cent of people don’t become immune after receiving the Sputnik V vaccine and the figure is similar for other vaccines. The reasons for this are unknown. Whether alcohol could be a factor hasn’t been investigated.

A 2012 study by researchers in Sweden found that low-to-moderate alcohol consumption slightly suppressed the inflammatory response to a vaccine against bacterial pneumonia, but had no impact on the immune response. The researchers defined this level of alcohol consumption as an average intake of less than 30 grams a day, about the same as three vodkas.

Gintsburg said that drinking 300 grams of vodka – about 12 UK measures, which contain a total of about 120 grams of alcohol – suppresses antibody production. But one glass of champagne would be OK, he said.

This week, Anna Popova, the head of the Russian Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing (Rospotrebnadzor), sparked a controversy in Russia  when she advised Russians to quit drinking alcohol two weeks before their first vaccine shot and for a further three weeks after the second. There is a three-week gap between injections so that is a total of eight weeks on the wagon.

Gintsburg told New Scientist that this was too stringent. “Of course, we are not talking about a complete ban on alcohol during vaccination. This is just a reasonable limitation of consumption until the body has formed its own immune response to coronavirus infection,” he said. “It is important to understand that excessive alcohol consumption can significantly reduce immunity and therefore reduce the effectiveness of vaccination or even make it meaningless. Moreover, this is true not only for Sputnik V, but also for any other vaccine.”

Kirill Dmitriev, CEO of the Russian Direct Investment Fund, which is funding the Sputnik V programme, says: “It applies to all vaccines, there is nothing particular about Sputnik vaccine that makes it more prone to alcohol consumption.”

Some people might want to err on the side of caution, says Paul Klenerman at the University of Oxford. “There’s no doubt that chronic excess alcohol has a significant impact on many aspects of immunity,” he says. “What isn’t clear is whether just a small amount would have any significant effect in [real-life settings]. So it is plausible and you could simply be very cautious and say avoid it. Different countries might end up giving different guidance.”

New Scientist made contact with a volunteer on the UK arm of the trial of the vaccine being developed by AstraZeneca and the University of Oxford. There was no instruction to abstain from alcohol around the time of vaccination, the volunteer said.

A volunteer on the UK-based Imperial College London vaccine clinical trial also said there was no requirement to avoid alcohol. However, an information sheet given to trial participants says that people with “suspected or known current alcohol or drug dependency” cannot take part in the study. It doesn’t say why.

Pfizer has said that there is no warning concerning alcohol consumption given to those receiving the vaccine it has developed with BioNTech. AstraZeneca, which has signed a deal to collaborate with the Sputnik V project, didn’t respond to a request for information on alcohol and vaccination.