Review: Coadministration of Adult Vaccines Both Effective and Efficient

As public health officials seek out better ways to protect the population against infectious illnesses like COVID-19 and influenza, a new review article makes the case for a strategy that is common in children but rare in adults: co-administration of vaccines.

The authors, writing in the journal Human Vaccines & Immunotherapeutics, argue co-administering vaccines could allow providers to more efficiently protect their patients without negatively impacting the efficacy of the inoculations.

The arrival of the COVID-19 vaccine in late 2020 led to a historically speedy uptake of the vaccine, reaching 70% in Europe within the first year, the authors said. Yet, that did not translate into higher uptake of other recommended vaccines.

“Despite existing recommendations, such a broad coverage in adults has not been reached in decades for influenza vaccination, not even in risk groups or elderly populations,” they wrote.

In the new review, the authors present key data related to co-administered vaccines in order to argue that the strategy has the potential to improve vaccination rates among a variety of disease areas. The authors—representing industry, academia, and public health organizations—said their review is not systematic, but rather a curation of relevant data based on their knowledge of the field and supplemented by a search of a scientific database.

One of the key reasons for suboptimal vaccine uptake is believed to be missed opportunities to vaccinate patients when they are in the clinic, as well as the burden of making multiple appointments for vaccinations. The premise behind co-administration of vaccines is that 2 or more vaccines can be successfully administered at the same time, thereby reducing the number of times a patient needs to visit a clinic.

However, they acknowledged that there have also been concerns about the potential for immunological interference and adverse reactions when simultaneously administering multiple vaccines. Such fears are mostly unfounded, the authors said.

“In reality, there are very few vaccine combinations and scenarios for which co-administration is contraindicated because of negative immunologic interference,” the authors said.

Meanwhile, they said, a wide variety of studies have shown that simultaneous administration of many of the most widely recommended vaccines is feasible. Vaccines that can be safely co-administered include vaccines against influenza, herpes zoster, and COVID-19, they said.

Co-administration was initially contra-indicated for the COVID-19 vaccine due to a lack of data. However, that stance was quickly reversed. Since co-administration has been allowed, the authors said, “very few risks have been observed and no serious issues have emerged.”

The investigators added that co-administration of vaccines is backed by years of practice. Children are routinely given vaccines simultaneously, and that fact has helped pediatric vaccine coverage surpass 90% across the US and Europe.

Adults, too, routinely get simultaneous vaccinations in certain circumstances, such as when they are preparing to travel abroad.

“Fast-approaching departure dates impose time constraints on travelers, and co-administration of several (sometimes up to 6) required, routine, or recommended vaccines is thus a common practice in travel clinics,” they wrote.

A study of healthy German travelers found the rate of side effects increased with the number of simultaneous vaccines a person received, but participants in the study perceived the tolerability of vaccine co-administration to be “excellent.”

Ultimately, the authors said extensive data and a strong safety profile exist in support of co-administration of vaccines. They hope health care providers will heed the data and move toward routine co-administration of adult vaccines.

“The success of these strategies may increase confidence of healthcare providers in routine adult vaccine co-administration, which might be of significant added value once integrated into regular practices to ensure compliance with recommendations,” they said.

Reference

Bonanni P, Steffen R, Schelling J, et al. Vaccine co-administration in adults: an effective way to improve vaccination coverage. Hum Vaccin Immunother. 2023;19(1):2195786. doi:10.1080/21645515.2023.2195786