Juan Camilo Vargas-Zambrano

Pertussis or whooping cough, caused by the bacteria Bordetella pertussis, is a highly contagious respiratory disease. Over the past century, whole-cell pertussis (wP) and acellular pertussis (aP) vaccines were developed and widely adopted, leading to a substantial reduction in the number of pertussis cases. Currently, various strategies are employed to protect different segments of the population, including primary immunization, toddler and school-age boosters, adult boosters, and vaccination in pregnancy (ViP). Nonetheless, pertussis remains a global health challenge with periodic outbreaks occurring every 2–5 years. The non-pharmacological measures implemented during the COVID-19 pandemic resulted in a drastic reduction in the circulation of B. pertussis. However, post-pandemic, there has been a resurgence in pertussis cases. This review aims to explore the post-pandemic global pertussis outbreaks and identify underlying trends to gain insights into the potential contributing factors. As of June 2025, pertussis outbreaks with diverse epidemiological patterns have been reported in at least 42 countries, including 30 aP and 12 wP vaccine-using countries. Some common observations among these countries include low infant immunization rates and an absence of vaccination programs for specific populations such as school-aged children, adults, and pregnant individuals. Additionally, in countries with extensive immunization schedules and high vaccination uptake, outbreaks have occurred in regions with low vaccination coverage rates (VCRs). Multiple interrelated factors may have contributed to the post-pandemic pertussis outbreaks, such as the cyclic epidemiology of pertussis, low VCR, waning vaccine-derived immunity, low uptake of boosters, and lack of lifelong protection through regular boosters. To effectively mitigate the incidence of pertussis outbreaks, it is crucial to administer regular booster vaccinations throughout an individual’s lifetime, with particular emphasis on at-risk populations and pregnant individuals. A Graphical Abstract is available for this article. Graphical Abstract

Background: The reported incidence of pertussis, a vaccine-preventable disease, has been increasing in recent years. This study aimed to estimate the burden of pertussis and the vaccination rate in Australian adults in primary care. Methods: Deidentified data for participants aged ≥18 years were extracted from the MedicalDirector (MD) primary care software from 2008 to 2019. We estimated the cumulative incidence of diagnosed pertussis in adults by age and risk groups and vaccine coverage in cases and a control group (not diagnosed with pertussis or a coughing illness). We also examined the incidence of unspecified coughing illness in the study population. Results: Of the 764,864 subjects included in the study, 1788 (0.2%) were diagnosed with pertussis between 2008 and 2019, corresponding to an average annual diagnosis rate of 76.9 per 100,000 population. About 31,110 (4.1%) of adults had an unspecified coughing illness. The highest rate was observed in 2011 and higher in females (63.3%), and the diagnosis rate was stable across all age groups. Underlying chronic conditions were more prevalent among pertussis cases than controls (58.7% vs. 18.8%), with asthma or chronic obstructive pulmonary disease (COPD) being the most common. Overall, 14% of cases received a pertussis vaccination during the study period. Diagnostic testing for pertussis was performed in 34.1% of pertussis cases. Estimated conservative costs per pertussis patient ranged from AUD 473 to AUD 909, with higher costs observed in individuals with complications. Conclusions: In the outpatient setting, there was a notable burden of pertussis among adults under 65 years of age, particularly those with underlying medical conditions, such as asthma and COPD, which appear to be significant risk factors. Due to the low rate of pertussis testing among all coughing illnesses, a proportion of non-specific coughing illness may be undiagnosed pertussis. The observed low vaccination rates highlight a need for increased awareness, improved diagnostic efforts, and prevention strategies in primary care.

Hepatitis B virus (HBV) surface antigen (HBsAg) seroprevalence was high before the national vaccine policy was introduced in Taiwan, indicating significant HBV infection rates. The success of the HBV immunization program and other preventive measures likely led to decreased HBsAg prevalence among pregnant women. This study reports on the HBV seroprevalence among pregnant women in Taiwan from 2016 to 2021, including those potentially affected by the universal hepatitis B vaccination at birth. This claim-based cohort study included pregnant women with hospital-based prenatal HBV screening data: 162,662 for HBsAg and 161,729 for HBeAg, from 2016 to 2021. Patient medical records were reviewed to collect information on demographic characteristics and other health conditions. Logistic regression models were used to identify risk factors associated with HBsAg and HBV e antigen (HBeAg) positivity. The seroprevalence for HBsAg and HBeAg during the study period was 4.0% and 0.6%, respectively. HBsAg positivity was highest among women born before July 1984 (pre-vaccination period; 8.6%), decreasing to 2.2% among those born between July 1986 and 1988 (national vaccination implementation) and further declining to 1.1% for those born after 1997. These data underscore the crucial role of large-scale immunization strategies in controlling HBV infections. Similarly, HBeAg positivity was highest among pregnant women born before the vaccination program (~ 1.0%), decreasing significantly to 0.4% for those born after 1989. The results showed geographic variations, potentially reflecting factors such as the mother’s age and foreign nationality. However, the birth year was the most crucial factor associated with HBV marker positivity. The implementation of national vaccination programs has demonstrated significant success in reducing HBV seroprevalence among pregnant women, which is particularly evident in the substantial decrease in HBsAg seroprevalence in Taiwan post-July 1986. These findings emphasize the importance of continued and consistent vaccination efforts, supporting the need for ongoing public health strategies to combat HBV infections effectively.

Pertussis is a highly contagious bacterial disease of the respiratory tract that can be prevented by vaccination. Before the COVID-19 pandemic, the vaccine coverage rate for the third dose of a DPT-containing vaccine was 86%, with large disparities among countries. Since 2022, many high-income countries have reported a resurgence of pertussis, especially in the European region, but the disease has also caused outbreaks in middle- and low-income countries, despite their less extensive disease surveillance capacities. This paper aims to review the incidence rates (IRs) of pertussis in high-, middle-, and low-income countries following the COVID-19 pandemic and to discuss the most relevant factors associated with the resurgence of the disease. The epidemiology of pertussis is highly variable and is influenced not only by the type of vaccine used but also by the specific characteristics of the disease, vaccine coverage rates, vaccination schedules, and the quality of surveillance. Since the cessation of COVID-19 measures, there have been significant pertussis outbreaks that could have been partially mitigated with higher coverage rates and more comprehensive pertussis vaccination throughout life.

The Global Polio Eradication Initiative (GPEI), launched in 1988, has successfully reduced wild poliovirus (WPV) cases by over 99.9%, with WPV type 2 and WPV3 declared eradicated in 2015 and 2019, respectively. However, as of 2024, WPV1 remains endemic in Afghanistan and Pakistan. Since 2000, outbreaks of circulating virus derived of polio vaccines (cVDPVs) have emerged in multiple regions, primary driven by low vaccine coverage rates (VCRs). The COVID-19 pandemic disrupted routine immunization, resulting in millions of unvaccinated children, and leaving many countries vulnerable to both WPV1 and cVDPVs outbreaks. This paper reviews the epidemiological landscape of poliomyelitis post the COVID-19 pandemic, and the strategies and challenges to achieve the global polio eradication.

Preventing perinatal transmission is important for hepatitis B (HepB) elimination. We conducted a retrospective cohort study to assess the interval between HepB birth-dose (HepB-BD) to second-dose (HepB-SD) vaccination on perinatal transmission. Among 39,313 infants born to HepB s-antigen (HBsAg)-positive mothers from a Korean national database 38,411 (97.7%) had completed timely immunophylaxis with HepB-BD 41,572 (99.8%) with hepatitis B immune globulin, and 1027 (2.6%) were HBsAg-positive at ≥ 9 months. Maternal factors (i.e. HepB e-antigen status, age, or nationality) were associated with an increased risk of infection whereas short gestational length decreased it. The HepB-BD - HepB-SD interval (<8 vs. ≥8 weeks) did not alter the risk.