Whooping Cough Is Spreading Quickly. Here’s How To Prevent It

Pertussis, also know as whooping cough, has surged this year, particularly during the back-to-school period, as my colleague Joshua Cohen noted last month. A few cases have recently been found near me in Frostburg, Maryland, involving two confirmed cases in students and three strongly suspected cases in members of the sick students’ households.

Pertussis infections occur in cyclical waves. Although not reflected in the graph above, the Centers for Disease Control and Prevention reports preliminarily “that more than five times as many cases have been reported as of week 40, reported on October 5, 2024, compared to the same time in 2023.” That’s 17,611 cases so far this year!

Cases of many respiratory diseases declined during the height of the COVID-19 pandemic because of relative social isolation from remote work and learning, as well as masking. Now that most people have given up on even modest efforts to protect themselves, we’re seeing a resurgence of infections.

Paul Offit, M.D., a virologist and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, put this all into perspective in an interview. “The first Pertussis vaccine was available in 1947; it was a whole killed bacteria,” he began. “At the time, there were as many as 8,000 deaths from pertussis every year, primarily in children.” The vaccine was quite effective but had a “difficult” safety profile, including fevers, seizures and fainting, but no long-term side effects. In 1991, we switched to an acellular vaccine, made from bits of protein, but not the whole inactivated bacteria. Offit described this as trading, “to some extent, efficacy for safety.” This also meant that multiple boosters were needed.

“The goal of any vaccine is to keep you out of the hospital,” Offit emphasized. “That’s the goal. The goal is not to prevent mild illness. You’re going to get mild illness. That’s true for influenza vaccine, the RSV vaccine, the COVID vaccine, the rotavirus vaccine.” Reasons we may never eradicate pertussis is because it is infectious for three weeks after someone starts coughing, unless antibiotics are given, and because it is commonly misdiagnosed.

But immune protection from vaccines wanes over time — that’s why we need periodic boosters. While the Allegany County Health Department declined to say if the ill children here were vaccinated, data shows that Maryland’s vaccination rate went from 87% for kindergarten students in 2020-2021 to 97% most recently (but only 63% for Allegany County early on). That’s better than the national average of 93%.

One change in practice is that of “cocooning,” or vaccinating all those around a pregnant woman to protect the newborn from pertussis. This is no longer recommended, in part because immunity is not very long-lasting. It’s much more effective to vaccinate a pregnant mother between 26-27 and 36 weeks gestation with Tdap (tetanus-diphtheria-acellular pertussis vaccine). She develops protective antibodies that last until the baby is 4-6 months old and can receive vaccines. Kids get six pertussis vaccines by the time they hit adolescence. Then, as adults, the CDC recommends a booster dose of either Tdap or Td (a different vaccine that protects against tetanus and diphtheria but not pertussis) every 10 years. It takes two weeks for protective antibodies to peak following immunization; that’s why the CDC recommends pregnant women be vaccinated early in the third trimester.

I would have expected the CDC to continue to recommend boosters against pertussis as well, and have reached out to the CDC and MD Department of Health for clarification.

An expert panel convened in 2022 to discuss changes in epidemiology (the pattern of infections) and vaccine strategies. Their report was notable to me for several observations. One is that cases are more commonly occurring in older kids and adults in whom the less reactive acellular pertussis vaccines have replaced older, original whole-cell pertussis vaccines. It’s easy to miss the diagnosis of pertussis — too few clinicians have experience with it, and many symptoms overlap with those of patients with COPD or asthma.

“Infection in older adults is also a concern because they may suffer serious complications and loss of independence, but could also be involved in grandparent care of vulnerable infants,” the authors note. “Consequently, vaccination could prevent pertussis spreading to very young grandchildren.”

The studies they cite raise ongoing questions about vaccine efficacy and strategies for adults, in particular. They do agree on the need for better vaccines, particularly for a live attenuated (weakened) vaccine, which would yield better immunity. BPZE1 is such a nasally administered live vaccine in development.

Until then, given a choice, Peter Kardos, M.D., the paper’s lead author, concurs that it seems safer to administer Tdap rather than a tetanus vaccine (Td) alone to adults at 10-year intervals.