Although COVID-19 vaccines have begun reaching people around the world, challenges remain to ensuring that the vaccines help those who are most vulnerable, according to an article co-authored by experts from Harvard T.H. Chan School of Public Health.
A February 3, 2021, article in Science Translational Medicine, co-authored by Wayne Koff, CEO of the Human Immunomics Initiative (HII) and adjunct professor of epidemiology; Jaap Goudsmit, CSO of HHI and adjunct professor of epidemiology and immunology; and 17 other researchers from around the globe, outlined the problems in developing and deploying vaccines that are safe and effective for vulnerable populations.
The authors noted that vaccines are often less effective in older people because of their aging immune systems and comorbidities. Populations in low- and middle-income countries (LMICs) may suffer from infections, malnutrition, and other health issues that can suppress immune responses to vaccines. Among both groups, vaccine uptake tends to be low, the authors added.
The article offered strategies to address the issues. For example, targeting children and young adults for vaccination may help achieve herd immunity and thus protect older populations, for whom COVID-19 vaccines may be less effective. In LMICs, improving COVID-19 surveillance to identify hotspots and including these countries in vaccine development programs could generate crucial data, boost confidence in vaccines, and increase vaccine uptake.
Other suggested options for optimizing the effectiveness of vaccines in vulnerable populations included offering high-dose vaccine regimens and formulating vaccines with adjuvants—ingredients that help boost immune response.
The article underscored the need to better understand immune function in aging and LMIC populations. Further study could shed light on “why some respond more effectively to infections such as SARS-CoV-2 than do others and, similarly, why some respond better to vaccines,” the authors wrote. “Defining these mechanisms of effective immunity will be critical for protecting vulnerable populations against future infectious disease outbreaks.”