Three years ago this week, the first Covid-19 vaccines began to reach the US public. Back then, it was hard to tell how the disruption of the pandemic would influence people’s health over the long-term. Now that the crisis has faded, those consequences are becoming clearer — and one seems to be reduced uptake of other vaccines.
The pandemic left “a significant and sustained impact on routine vaccination programs,” researchers from Merck and Avalere Health wrote in a recent journal article. A surge of misinformation, conspiracy theories and political rhetoric against vaccinations in general may have lasting effects on trust and people’s willingness to get inoculated. But practical hurdles contributed to the problem, too: People who missed immunizations when they skipped regular in-person medical visits during Covid lockdowns.
In Canada, for example, a whole cohort of adolescents lags in vaccination for human papillomavirus, or HPV. The HPV vaccine prevents a common virus that can cause genital warts. Most people who are sexually active will get it at some point, even if they don’t have symptoms. For some people who don’t clear the infection, the latent virus can cause cancer years after exposure. The US recommends the shots for adolescents at 11 or 12 years; in Canada, school-based programs typically administer them in grades 4 through 7.
The disruption in Canada isn’t from mistrust in vaccines – it’s simply because some people missed in-person schooling when they would normally get immunized, says Samara Perez, an assistant professor at McGill University who has researched the issue.
“Canadians are just very pro-vaccination and very abiding of their health ministers,” Perez says. Yet she surfaced public data showing drops in HPV vaccination rates across Canada, most notably in Ontario, the largest province by population. Only 16% of 12-year-olds were up to date on HPV vaccinations in the school year ending in 2022, compared with 58% in the school year before Covid.
While many vaccines protect from infectious diseases, the HPV vaccine actually prevents several types of cancer caused by the virus. In the US, about 37,000 cases of cancer annually are attributable to HPV, according to the Centers for Disease Control and Prevention. The HPV vaccine was approved for use in the US in 2006, but it faced resistance since some parents oppose giving children a shot to protect them from something transmitted by sexual contact.
Canada hasn’t caught up for all the doses missed in school-based programs, Perez says: “It’s like we’ve gone back 20 years.”
The consequences may not be seen for decades, when people who missed vaccinations develop cancers that could have been prevented.
US parents may have delayed early childhood and adolescent vaccines during the pandemic, thinking they would make up for missed doses after the pandemic, says Gregory Zimet, professor emeritus of pediatrics at Indiana University. Most states don’t require HPV vaccination for school enrollment, so kids may be less likely to make up missed doses.
“There are going to be cohorts that remain under-vaccinated for the rest of their lives,” Zimet says. — John Tozzi