Adult Vaccine Coadministration Is Safe, Effective, and Acceptable: Results of a Survey of the Literature

Coadministration of vaccines in children is a long-standing practice that has proven to be safe and effective in improving the efficiency of vaccine administration, thereby increasing immunization coverage rates. As the number of vaccines routinely recommended for adults increases, and with limited opportunities for adults to have preventive health touchpoints with providers, adult vaccine coadministration should be considered as a routine practice to improve vaccination coverage rates and public health. A review of existing literature was conducted to examine the potential reactogenicity and impact on effectiveness when co-administering vaccines to adults.

Medline was searched for research articles with the search term "influenza vaccine" or "vaccination," combined with the search terms "simultaneous," "concomitant," "concurrent," and "combination." Another search of Medline was conducted on the search term "influenza vaccine" or "vaccination" combined with the following individual search terms: "RSV," "COVID," and "Tdap." The references of extracted articles were also examined for potential other relevant articles.

Adult vaccine coadministration is safe for all the combinations we assessed. Most adverse events (AEs) were generally mild to moderate and of short duration. Some studies showed slightly more reactogenicity with coadministration but few or no serious AEs or safety signals. Nearly every study confirmed that coadministration had no significant effect on immune response for either vaccine. The benefits of vaccine coadministration outweigh the risks. It increases convenience for vaccinees, reduces the number of missed opportunities to vaccinate, and contributes to efficient use of healthcare resources.