Greg. G Wolff, an Epidemiologist with the Armed Forces Health Surveillance Branch recently published a study in the Journal Vaccine titled, Influenza vaccination and respiratory virus interference among Department of Defense personnel during the 2017–2018 influenza season. The study examined virus interference in a Department of Defense population, this refers to the increased risk of other respiratory viruses as a result of, in this case, the influenza vaccine. The study found that virus interference varied among vaccinated individuals for individual respiratory viruses, and found that for coronaviruses in particular, in this study, those who had been vaccinated with the flu vaccine had a 36 percent higher risk of contracting it. This doesn’t apply to the new coronavirus, but instead already existing circulating coronaviruses.
The study compared the vaccination status of more than two thousand people with non-influenza respiratory viruses to more than three thousand people with pan-negative results. The vaccination status of more than three thousand cases of influenza were compared to three different control groups, and appropriate adjustments were made.
The study points out that recently published studies have “described the phenomenon of vaccine-associated virus interference; that is, vaccinated individuals may be at increased risk for other respiratory viruses because they do not receive the non-specific immunity associated with natural infection.” The study goes on to emphasize that “There has been limited evidence that the influenza vaccine may actually be associated with the virus interference process. Other studies have found no association between influenza vaccination and increased respiratory virus risk.”
Other studies have found no association between the flu vaccine and an increased risk for other respiratory viruses, but when looking specifically at coronavirus, Wolff’s study found that “Vaccine derived virus interference was significantly associated with coronavirus and human metapneumovirus; however, significant protection with vaccination was associated not only with most influenza viruses, but also parainfluenza, RSV, and non-influenza virus coinfections.”
Metapneumovirus causes both upper and lower respiratory disease in all ages.
Out of the 6120 people in the study with respiratory viruses other than influenza, those who received an influenza vaccine actually had a decreased risk of having other respiratory pathogens compared to the unvaccinated group. Again, it’s important to be specific with what respiratory pathogens one may have an increased risk of contracting as a result of being vaccinated against influenza. This is why for some pathogens, no increased risk was observed, and in some cases a decreased risk was observed. But again, specifically for coronavirus, a significant increased risk was observed.
With regards to the coronavirus and human metapneumovirus, the data in this study showed an increased risk of contraction within vaccinated individuals to be 36 percent greater.
The laboratory data in our study showed increased odds of coronavirus and human metapneumovirus in individuals receiving influenza vaccination…In our disease specific investigation, virus interference trends were noticed for coronavirus and human metapneumovirus…Examining non-influenza viruses specifically, the odds of both coronavirus and human metapneumovirus in vaccinated individuals were significantly higher when compared to unvaccinated individuals (OR = 1.36 and 1.51, respectively)
The study concluded that:
Receipt of influenza vaccination was not associated with virus interference among our population. Examining virus interference by specific respiratory viruses showed mixed results. Vaccine derived virus interference was significantly associated with coronavirus and human metapneumovirus; however, significant protection with vaccination was associated not only with most influenza viruses, but also parainfluenza, RSV, and non-influenza virus coinfections.
But overall, the results showed “little to no evidence supporting the association of virus interference and influenza vaccination.”
Furthermore, a study published in the same journal, Vaccine, found that“Among children there was an increase in the hazard of ARI (acute respiratory illness) caused by non-influenza respiratory pathogens post-influenza vaccination compared to unvaccinated children during the same period…Patient perceptions of illness following influenza vaccination may be supported.”
The Department of Defense has a Global Respiratory Pathogen Surveillance Program (DoDGRS), it’s a DoD-wide program established by the Global Emerging Infections Surveillance and Response System (GEIS). This is how Wolff was able to gather all of his data with regards to who had been vaccinated with the influenza virus, and what other illnesses they experienced. The Defense Health Agency/Armed Forces Health Surveillance Branch – Air Force Satellite Cell (DHA/AFHSB – AF) and United States Air Force School of Aerospace Medicine (USAFSAM) also provided access to the data.