An article published in The Lancet by Toback and others on November 17, 2021 discusses  this issue. 

The safety and immunogenicity profile of COVID-19 vaccines when administered  concomitantly with seasonal influenza vaccines has not yet been reported. This study  therefore aimed to report the results of a sub study within a phase 3 UK trial by evaluating the  safety immunogenicity of the efficacy of the COVID-19 vaccine, Novavax vaccine, when  administered with licensed seasonal influenza vaccines. 

The first 400 participants meeting the main study entry criteria, that is with no contraindication  to influenza vaccination, were invited to join this sub study.  

Participants in the main study were randomly assigned to receive two intramuscular injections  of either Novavax or Placebo 21 days apart. Participants enrolled into the sub study were co vaccinated with a single intramuscular age appropriate flu vaccine as in the quadrivalent for  those aged 18-64 and the adjuvanted trivalent for those above or equal to 65 years of age.  The influenza vaccine was administered in an open label manner and at the same time as the  first study injection.  

Reactogenicity was evaluated through an electronic diary for seven days after vaccination in  addition to monitoring for unsolicited adverse events. 

Immunogenicity was assessed with the influenza, haemagglutination inhibition and SARS CoV-2 anti-spike protein. Vaccine efficacy against PCR confirmed symptomatic COVID-19  was assessed in participants who were seronegative at baseline, received both doses of study  vaccine or placebo, had no major protocol deviations affecting the primary endpoint and had  no confirmed cases of symptomatic COVID-19 from the first dose until six days after the  second dose.  

Between September 28 and November 28, 2020, a total of 15,187 participants were  randomised into the main phase 3 trial of which 15,139 received treatment, 7,569 received dose one of Novavax and 7,570 received dose one of placebo.  

431 participants were co-vaccinated with seasonal influenza vaccine in the sub study. 217  received Novavax plus the influenza vaccine and 214 received placebo plus the influenza  vaccine.  

In general, the sub study participants were younger, more racially diverse and had fewer  comorbid conditions than those in the main study.  

Reactogenicity events were more common in the co-administration group than in the Novavax  group alone. Tenderness 113, 54.9% of 174 versus 592, 53.3% of 1,111 or pain 69, 39.7%  versus 325, 29.3% at injection site, fatigue 48, 27.7% versus 215, 19.4% and muscle pain 49,  28.3% versus 237, 21.4%. 

Incidences of unsolicited adverse events, treatment related medically attended adverse events  and serious adverse events were low and balanced between the co-administration group and  the Novavax alone group.  

No episodes of anaphylaxis or deaths were reported within the sub study. Co-administration  resulted in no change to influenza vaccine immune response although a reduction in antibody  responses to the Novavax vaccine was noted.  

Novavax vaccine efficacy in the sub study, i.e. participants aged 18 to less than 65 years was  87.5% and in the main study was 89.8%.  

This study showed the safety, immunogenicity and efficacy profile of the COVID-19 when co administered with seasonal influenza vaccine.  

The results suggested that concomitant vaccination was a viable immunisation strategy. 

This study showed no early safety concerns with the concomitant administration of Novavax  with the influenza vaccine.  

Immunogenicity of the influenza vaccine was preserved with concomitant administration  although there was a modest decrease in the immunogenicity of the Novavax vaccine found.  

Vaccine efficacy in those aged 18 to less than 65 years appeared to be preserved in those  receiving both vaccines compared with those vaccinated with Novavax alone.  

The London General Practice, the leading London doctors’ clinic in Harley Street commends  all those eligible to have both the influenza vaccine and the COVID-19 vaccine. It commends  the government on its vaccination programme and encourages all those eligible to be  vaccinated appropriately. 

Dr Paul Ettlinger 
BM, DRCOG, MRCGP, FRIPH, DOccMed

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