Is it wise to get a COVID-19 booster and a flu vaccine at the same time?
Studies suggest that combining influenza and flu vaccination is safe and any increase in side effects is mild.
- 25 October 2022
- 4 min read
- by Linda Geddes
Few people look forward to being jabbed, let alone receiving two vaccines at once. But with COVID-19 surging in many northern hemisphere countries just as influenza season is about to take off, some health authorities are advising older or clinically vulnerable people to get a COVID-19 booster and seasonal influenza vaccine at the same time.
Safety first
Although it may feel unusual to be offered a second vaccine at the same time as your annual flu shot, infants often receive multiple vaccinations in single visit – and sometimes even protection against multiple diseases in a single shot. For example, a baby might be given an inactivated polio vaccine (IPV) in one arm or leg and DTP vaccine in another arm or leg during the same visit. And the DTP vaccine contains immune-stimulating elements (antigens) from three different pathogens: diphtheria, tetanus and pertussis (whooping cough).
There was also no difference in the immune response to either the COVID-19 or influenza vaccine when they were given together, or alone, suggesting that either combination should be equally effective at preventing disease.
The reason is because vaccines need time after administration, and often several doses, to stimulate a protective immune response. Children need to be given their vaccines as quickly as possible to protect them against fatal diseases during the early months of their lives, and beyond. Giving several shots at once also means fewer trips to the clinic, saving parents time and money, as well as potentially being less traumatic for the child.
Similarly, time pressures imposed by busy schedules or pending departure dates also mean that adults attending travel clinics are sometimes offered several travel vaccinations at the same time.
Have you read?
Many studies have looked at the effects of giving different combinations of vaccines, and although a small number of specific combinations may cause mild to moderate side-effects, these are temporary and do not cause any lasting damage. Regulators use the results of such studies to inform vaccination programmes in their countries.
COVID-19 plus flu
In the case of COVID-19 boosters and influenza vaccines, the UK's Combining Influenza and COVID-19 vaccination (ComFluCOV) trial investigated the impact of giving 679 adult volunteers their second dose of either the Pfizer/BioNTech or Oxford/AstraZeneca COVID-19 vaccines alongside one of three different seasonal flu vaccines in the opposite arm. A separate group was given a placebo injection instead of a flu jab, followed by a flu jab 21 days later.
Injection site pain and fatigue were the most commonly reported side effects – with no significant difference in these reactions for four of the six COVID-flu combinations, and only a slight increase in the number of people who reported at least one side effect when two of the flu vaccines were given alongside the second COVID-19 shot – predominantly fatigue, headache, and muscle aches. All these side effects were recorded as mild or moderate.
There was also no difference in the immune response to either the COVID-19 or influenza vaccine when they were given together, or alone, suggesting that either combination should be equally effective at preventing disease.
Beneficial boost
The World Health Organization has warned that the potential co-circulation of COVID-19 and seasonal influenza this autumn and winter will put vulnerable people at increased risk of severe illness and death, as well as increasing pressure on hospitals and exhausted healthcare workers.
Many of those most at risk of severe COVID-19, such as people over 60 years old, pregnant women and those with comorbidities or underlying conditions are also at high risk of experiencing a serious influenza infection – so it would be wise to accept the offer of both vaccines, rather than opting for one or the other.
Protective antibodies triggered by both vaccines are also known to wane over time, and the influenza strains circulating now are different to those that dominated last year. This means that even if someone received an influenza or COVID-19 vaccine last year, they will still benefit from the vaccines being offered now.
