Can you take the COVID-19 or Influenza vaccines on the same day?

The coronavirus pandemic in 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus-2, (SARS-CoV-2), has infected millions and claimed more than 5,000,000 lives. According to the World Health Organization, globally, around 290000-650000 people are afflicted with influenza each year. Studies have shown that influenza can cause death in people over 65 years old and infants under 2 years of age.

Study: Safety, immunogenicity, and efficacy of a COVID-19 vaccine (NVX-CoV2373) co-administered with seasonal influenza vaccines: an exploratory study of a blinded, randomised, placebo-controlled, phase 3 trial. Image Credit: Prostock-studio/Shutterstock


As a preventive measure influenza vaccination is recommended in a number of countries. Researchers have pointed out that the COVID-19 vaccination program could be in conjunction with influenza vaccination programs in a majority of countries, since the timing of both vaccinations could overlap. There is no research to date regarding the co-administration COVID-19 vaccinations and other vaccines. This is because, during the phase 3 trials of COVID-19 vaccines, scientists either did not exclude candidates who had been recently vaccinated, or who were scheduled to receive vaccines within one week of receiving COVID-19 vaccine. It is crucial to know the impact of multiple vaccinations on immune responses and the safety of vaccines.

In accordance with the current guidance in the UK, individuals can take both vaccines, with a minimum of seven days of time between the two. The US Centers for Disease Control (CDC) recommends that people wait 14 days between vaccines. However, the need for multiple visits to health care clinics to receive vaccinations could hinder the rate of compliance and uptake of vaccinations. Therefore, it might be crucial to encourage people to take the vaccines, i.e., COVID-19 and influenza, in one visit instead of on separate days.

Scientists conducted a substudy as part of a phase 3 UK trial. They reported on the safety, immunogenicity, and effectiveness of the NVX CoV2373 CoVID-19 vaccine administered with licensed seasonal influenza vaccines. The study was published in Lancet Respiratory Medicine.

Principal conclusions

The authors claim that this substudy is the first to document the safety, immunogenicity, and effectiveness of any COVID-19 vaccine when co-administered with a seasonal influenza vaccine or other vaccination. This study found no proof of the interference of the COVID-19 vaccine with quadrivalent influenza cell-based vaccine. The exploratory study involved 15187 participants. The study was conducted between September 28 th, 2020 and November 28 th in 2020. Participants were young, diverse and had fewer comorbidities.

Local and systemic reactionogenicity reactions such as discomfort or pain at the injection site, fatigue, and muscle pain were more frequent in the co-administration group compared to those who received only the NVX-CoV2373 vaccination. Occurrences of unsolicited adverse events or serious adverse reactions that required medical attention were minimal in both groups. Researchers have found that no clinically relevant pattern of increased reactogenicity was found in any of the study groups.

In the study group there was no anaphylaxis or death was observed. It is important to note that the co-administration of COVID-19 in conjunction with influenza vaccine did not result in an alteration in the immune response to the influenza vaccine. However there was a decrease in the antibody responses to NVX-CoV2373 was observed. The NVX-CoV2373 vaccine proved effective in 87.5 percent of subjects, whereas the control vaccine showed 89.8 percent effectiveness.

Strengths and weaknesses

Researchers stressed that the major strength of this substudy is its study design that is placebo-controlled. Another benefit of this study is its compatibility with the UK’s national influenza vaccination policy, which includes both types of influenza vaccines (adjuvanted and unadjuvanted).

This substudy has a limited sample size, with only a few participants older than 65 years old. Other limitations of the study include the absence of randomization when recruiting influenza substudy participants, a limited number of endpoints of the substudy’s efficacy and the absence of a formal, pre-defined statistical assessment of the immunogenicity as well as other. Future studies could create more robust randomized groups, such as NVX-CoV2373 with influenza vaccine, NVX-CoV2373 plus placebo, influenza vaccine plus placebo, and placebo and placebo groups. Scientists also pointed out that the evaluation of neutralizing antibody titers might have been beneficial in the investigation of immunogenicity. Researchers also noted that the open-label approach that was used to administer the influenza vaccine was a limitation.


This is the first study to show the safety, immunogenicity and effectiveness of a COVID-19 vaccine combined with seasonal influenza vaccines. The data obtained showed no adverse reactions from administering both the NVX-CoV2373 and influenza vaccines in tandem. In this way, the immunogenicity of the influenza vaccine was maintained; however, scientists observed that there was a slight decrease in the immunogenicity of the NVX CoV2373 vaccine. Another striking observation among the age group 18-65 was that the effectiveness of the vaccine was preserved in people who received both the vaccines, in contrast to those who received only NVX-CoV2373.

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Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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