A few days ago, Shen Hongbing, director of the Central Disease Control and Prevention Department, said: "The number of cases in 2022 and 2023 has reached 38,295 and 37,034, respectively."
1. Pertussis incidence data in mainland China
If you don't know this number, let's take a look at the ranking of cases since the publication of the "report" data of notifiable infectious diseases in 1985 (figure below):
Ranked No. 1: 193001 cases, 211 deaths (1984)
Ranked 2nd: 121414 cases, 143 deaths (1985)
Ranked 3rd: 76,777 cases and 58 deaths (1986)
Ranked 4th: 54,065 cases and 80 deaths (1987)
Ranked 5th: 39,063 cases of illness and 2 deaths (2022)
Ranked 6th: 37,427 cases and 4 deaths (2023)
The cumulative data reported in the two months of "January 2024" and "February 2024" are: 32,380 cases of cases and 13 deaths (figure below).
In other words, the number of cases in the first two months of 2024 is already close to that of the whole of 2023, and the number of reported deaths has exceeded that of 2018-2023 combined. Based on the data alone, the number of reported pertussis cases in 2024 is expected to be the "highest" number of reported pertussis cases in 37 years.
*The above data are from the journal Disease Surveillance, there are some differences between the data and the news, and the above data are related to surveillance reporting, and the real burden of disease is higher than the reported data
2. Introduction to whooping cough
Pertussis (below) is an acute respiratory infection caused by the bacillus pertussis (Bordetella pertussis).
According to the World Health Organization (WHO), there are still "millions" of morbidity and "thousands" of related deaths every year. "Infants" and "young children" are particularly susceptible to severe pertussis and have a higher risk of death. It is important to emphasize that the symptoms of whooping cough include:
1. Catarrhal phase: lasts for 1-2 weeks, and the symptoms are similar to the "common cold", including runny nose, slight cough, fever, etc.;
2. Spasmodic period: lasting 2-4 weeks or longer, episodic cough, the most typical symptom is "chicken-like cough", and the attack may be accompanied by vomiting, suffocation, etc.;
3. Convalescence: The cough gradually lessens but may last "weeks to months".
As a "former patient" who was "not diagnosed in time", I went to a tertiary hospital after having symptoms, and was diagnosed with bronchitis after blood sampling and imaging examinations, and then prescribed cefdinir (the doctor's original words: I saw that there was nothing to do, prescribe some antibiotics and Chinese patent medicine first) and then took it for two weeks to no avail, and then "coughed for about three months" The symptoms disappeared.
So, can the domestic pertussis report data really reflect the true burden of disease?
3. Vaccines and pertussis in adults
Although pertussis is a vaccine-preventable disease, the epidemiology of the mainland can be said to reflect the shortcomings of the vaccine immunization program.
There are "3" vaccines approved for the prevention of pertussis in China, including diphtheria-pertussis vaccine (free of charge), quadruple vaccine (self-paid, more protection against Haemophilus influenzae type b than diphtheria-pertussis vaccine) and quintuple vaccine (self-paid, more prevention of polio than quadruple vaccine).
The immunization schedule for the first two vaccines is one dose each at 3, 4, 5, and 18 months of age, and the immunization schedule for the quintuple vaccine is one dose each at 2, 3, 4, and 18 months of age.
That is, after 1 1/2 years of age (18 months of age), there is no vaccination containing pertussis.
In addition, if you have not received the above three vaccines according to the immunization schedule before the age of 6, you can only receive the "diphtheria" vaccine (only to prevent diphtheria and tetanus, not pertussis) from the age of 6.
So what are the results of this immunization program? We can refer to a few key results from the study conducted by Zhejiang University during the pandemic:
1. Among the 4459 volunteers aged 0~59 years old who participated in the study, the overall positive rate of anti-pertussis toxin antibody (anti-PT IgG) was "29.80%" (less than 1/3 had antibodies);
2. From the perspective of age group, the positive rate of 1~2 years old was the highest (81.44%), and the antibody level decreased rapidly after that (figure below);
The lowest (4.72%) in 10~14 years old, "more than 50%" of "over 7 years old" volunteers could not detect antibodies, and the positive rate of anti-PT IgG in all age groups of 5~59 years old was "less than 10%" (figure below).
3. From the perspective of infection, the proportion of people with anti-PT IgG ≥ 80 IU/mL (recent infection) in the 10~14 years old, 15~29 years old and 40~59 years old group is about 0.9%, 0.3% and 1.1%, respectively.
In summary: (1) the immunity persistence of existing vaccines according to the current immunization schedule is insufficient, (2) the vast majority of people over 7 years old lack protection against pertussis, and (3) the population is at high risk of pertussis.
In addition, not only China, but also some countries and regions in Europe and the United States (below) have also found an increase in whooping cough in adolescents and adults.
Fourth, the stones of other mountains
How to reduce the incidence of whooping cough, especially in older age groups, has been a global concern.
As a result, a booster form of diphtheria-pertussis vaccine (Tdap or Tdap-IPV) has been approved as a booster dose in children with diphtheria, tetanus
In addition to the booster vaccination (1 booster every 10 years) that has been approved for the vaccine to strengthen pertussis prevention, some countries' recommendations can be referred to in the chart below.
In addition, Tdap can also be used for pregnant women to vaccinate, thereby reducing the risk of neonatal whooping cough, such as the United States and India recommend vaccination at 27~36 weeks of pregnancy, Canada recommends vaccination at 27~32 weeks, and some other countries can refer to the following figure for Tdap recommendations during pregnancy.
As it stands, the best way to effectively control the incidence of pertussis is to improve surveillance and testing capacity (to optimize diagnosis) and consider optimizing immunization schedules and vaccine types (including Tdap vaccine) in addition to maintaining the current vaccination rate of diphtheria-pertussis vaccine in children, but only the former can be achieved so far.
sincere
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