Reasons for researching a new generation pertussis vaccine

Ms. Juliet Lautenbach, a civil servant and fantasy author living in Canberra, Australia, had never paid attention to whooping cough. During pregnancy and while taking care of their daughter, mother and child were vaccinated with free whooping cough vaccine along with many other standard vaccines.

Five years after giving birth, Lautenbach and her daughter suddenly developed a persistent cough. At the office where she worked, another colleague also coughed a lot and said he had whooping cough. This made Lautenbach understand what disease she and her daughter had.

Whooping cough is described by Lautenbach as persistent even in adults, feeling as if the body has stretched the muscles along the ribs. Her daughter has asthma, coughs for many days and makes a characteristic hissing sound when gasping for air. Once driving to the hospital, Mrs. Lautenbach had to stop every 10 minutes to prevent her daughter’s acute asthma attack.

Luckily, her daughter survived that bout of whooping cough. Ms. Lautenbach said the vaccine may have saved her life, but it was not perfect because the antibody level had gradually decreased.

Whooping cough is a respiratory disease caused by the bacteria Bordetella pertussis. The disease is contagious and recurs periodically. In 2024, the disease increased in some countries after the Covid-19 lockdown. In some European countries, more cases were reported in January-March 2024 than in all of 2023, and the number of vaccinated women has decreased. In England, 58.6% of pregnant women were vaccinated between 2023 and 2024, down from 2019-2020.

Regarding vaccines, the DPT combination shot was first introduced in 1948 and is still used today to combine prevention of diphtheria, tetanus and pertussis. Recently, six-in-one vaccines were launched, combining protection against more diseases. Before these vaccines were available, the average mortality rate was 10% in young children. After the vaccine became available, the number of deaths and pertussis infections decreased rapidly. Currently, the vaccine’s effectiveness in preventing disease ranges from 79% to 84%, about 91% in preventing hospitalization.

Daniela Hozbor, an expert on bacteria and vaccines at the Institute of Biology and Molecular Biology at the National University of La Plata, Argentina, explained that whooping cough is very contagious. If a sick person is placed in a closed room for about an hour, 90% of people around them can be infected. Therefore, vaccines are very important to help prevent bacteria from being transmitted.

Third generation vaccines

According to Camille Locht, research director at the French National Institute of Health and Medical Research (Inserm), the world has a two-tier system for whooping cough vaccines. First-generation whole-cell vaccines with many side effects, currently widely used in some low- and middle-income countries. Acellular vaccines are used in countries with more economic potential.

Locht said the vaccine helps prevent disease and reduces mortality from whooping cough but does not prevent the body from being infected with the virus. Vaccines gradually lose their protective effect as bacterial strains evolve.

The age of infection also varies. Previously, unvaccinated newborns would be infected with the disease. Currently, in addition to the deaths in the above mentioned group of children, the rate of infection is high in the 10-19 year old group, when the protective ability of the vaccine has decreased sharply.

According to Locht, simply increasing the frequency of booster injections is not feasible. The reason is that people tend to miss booster shots while their immunity to the disease gradually decreases. Therefore, many years later, he returned to research to prepare a vaccine containing live but weakened pertussis bacteria.

The new generation vaccine, called BPZE1, uses weakened pertussis bacteria. The vaccine will undergo phase three clinical trials in 2025, to ensure the vaccine is safe and effective in all age groups. Locht said that besides minor side effects such as runny nose, the team has not recorded other side effects related to the vaccine.

Distribution of this vaccine could begin in 2026 or 2027. Locht expects the BPZE1 vaccine to be more effective than current vaccines.

Hozbor’s team is developing vaccines that can be delivered into the body through the nose or muscle. Hozbor hopes human trials will yield similar positive results as animal research, but it will take time and money.

However, experts also raise the issue that the new vaccine cannot completely solve the problem of people not being vaccinated. Hozbor emphasized the need to continue to create more confidence in vaccines, because whooping cough is very contagious, the minimum vaccine coverage level needs to be 90% or 95% to prevent the disease.

Another barrier to vaccines is the cost of vaccination. For example, in Malaysia, whooping cough vaccine is only available through vaccination services. Locht expects the BPZE1 vaccine to be cheaper than existing options.