Common concern | These children do not need to get a booster shot of polio vaccine! Attachment: Questions and answers about the recent inspection of polio vaccines

Recently, many parents may have received the notice shown below, requiring children born between March 1, 2016 and September 30, 2019 to check their polio vaccination status.

First of all, don't worry, there is " no " polio outbreak (not even any cases), and there is "no" problem with the previous polio vaccine, but "some children" need to strengthen their protection against "type 2 polio virus". The following is the Q&A section: 1. Why do children with the above-mentioned birth dates need to be checked? Answer: Because it is necessary to screen children who have only one dose of vaccination history containing type 2 polio virus antigen . At that time, the immunization program of our country's immunization program vaccines (commonly known as "class 1 vaccines" or "free vaccines"), the polio vaccine immunization program at that time was "1 shot of inactivated polio vaccine (IPV)" + "3 doses of bivalent live attenuated polio vaccine (bOPV)" (that is, IOOO program).

2. Was there any problem with the immunization program at that time ? Answer: There was no problem with the immunization program at that time, but because IPV can prevent 3 types of polio virus (type 1, type 2, type 3), while bOPV can only prevent 2 types of virus (type 1, type 3), the immunization program at that time had weak protection against type 2 virus , so an additional dose of IPV that can prevent type 2 virus was needed as a reinforcement.

3. Hasn’t the type 2 polio virus been eradicated? Answer: Although the world has eradicated the type 2 and type 3 polio “wild viruses”, due to the use of live attenuated polio vaccines (OPV), the living weak viruses in the vaccine “ regained their pathogenicity ” during the circulation of the population, so “polio vaccine-derived viruses (VDPV)” that can cause polio like wild viruses have appeared in many countries around the world.

****Especially, the number of reported cases of "flaccid paralysis (AFP)" caused by "type 2 polio vaccine-derived virus (VDPV2)" in the world in recent years has reached hundreds (see the figure below, data as of February 20, 2024), so protection against type 2 virus is still very important.

4. Is it necessary for China to prevent type 2 poliovirus? Answer: It is necessary because there is a risk of importation . Although "China has not reported any cases of polio for many years", Afghanistan, Tajikistan and Pakistan, which border China, have reported AFP and infection cases caused by VDPV2 in 2021.

In addition, some African countries have also experienced polio outbreaks caused by VDPV2. Therefore, with the global population movement, the possibility of cross-border transmission of the virus exists . For example, VDPV2 has been found in "environmental samples" in the United States and the United Kingdom in recent years. **5. Which children need to get a booster shot of polio vaccine? **Answer: Children born between March 1, 2016 and September 30, 2019 and who have only received one dose of vaccine containing type 2 virus components , if the green book or electronic vaccination record only has one shot of "pentavalent vaccine/IPV/sIPV", and the others are "bivalent live attenuated polio vaccine/bOPV", then they need to get a booster shot of IPV or sIPV.

6.Is there any difference between IPV and sIPV? Answer: There is no substantial difference between the two. The former is an imported Salk strain, while the latter is a domestic Sabin strain.

7. Can I get a booster shot with the pentavalent vaccine? Answer: No , because I am older than the age recommended in the instructions or do not meet the immunization schedule, I can only get the "IPV/sIPV" for free. There is no need to get the pentavalent vaccine unless there are special reasons.

8. Which children in this age group do not need to get a booster shot of polio vaccine? Answer: It depends on the region and vaccination history. Region: Children born in Shanghai generally do not need to consider this issue, because Shanghai adopted the 2+2 program during that period, and children born on the above dates have received at least 2 doses of IPV containing type 2 polio virus antigens.

Vaccination history: If the child in your family has received ≥2 doses of "pentavalent vaccine/IPV/sIPV" and "has a record of 4 doses of polio vaccine" (regardless of whether it is pentavalent vaccine, IPV, or OPV), then there is "no need" to get an IPV booster shot (see the figure below for details).

9. If you don't need to boost polio, what else can you get? Answer: Children born between March 1, 2016 and September 30, 2019, and now aged 4 to 8 , can get some vaccines they haven't received before, including: inactivated enterovirus 71 vaccine (2 doses for the full course, ≥ 1 month interval), 13-valent pneumococcal conjugate vaccine (1 dose), 23-valent pneumococcal polysaccharide vaccine (high-risk groups, 1 dose), influenza vaccine (1 dose per year), etc., to provide more comprehensive protection for children.

The above information can be used as a reference for the polio vaccine booster issue that parents have been concerned about recently. Because the notification methods and immunization procedures may differ from place to place, there may be slight differences in the actual implementation. This graphic and text are for reference only.

willing

=丸= Disclaimer: This article was created out of personal interest, only to allow more ordinary people to have a clearer understanding of vaccines. The content and views do not represent any organization, unit, or institution, and have not accepted any form of sponsorship. All pictures are from public online platforms. If the content is incorrect, everyone should do more self-criticism (not).