

LETTER TO EDITOR 

Year : 2021  Volume
: 12
 Issue : 1  Page : 49 

Expected RATE of vaccineassociated paralytic poliomyelitis: A simulation analysis regarding transition from the trivalent to bivalent oral poliovirus vaccine
Sora Yasri^{1}, Viroj Wiwanitkit^{2}
^{1} Private Academic Practice, Dr. DY Patil University, Pune, Maharashtra, India ^{2} Honorary Professor, Dr. DY Patil University, Pune, Maharashtra, India
Date of Submission  07Aug2019 
Date of Acceptance  26Jun2020 
Date of Web Publication  27May2021 
Correspondence Address: Sora Yasri Private Academic Practice India
Source of Support: None, Conflict of Interest: None  Check 
DOI: 10.4103/ijpvm.IJPVM_293_19
How to cite this article: Yasri S, Wiwanitkit V. Expected RATE of vaccineassociated paralytic poliomyelitis: A simulation analysis regarding transition from the trivalent to bivalent oral poliovirus vaccine. Int J Prev Med 2021;12:49 
How to cite this URL: Yasri S, Wiwanitkit V. Expected RATE of vaccineassociated paralytic poliomyelitis: A simulation analysis regarding transition from the trivalent to bivalent oral poliovirus vaccine. Int J Prev Med [serial online] 2021 [cited 2021 Oct 17];12:49. Available from: https://www.ijpvmjournal.net/text.asp?2021/12/1/49/316996 
Dear Editor,
Poliomyelitis is a preventable infection by vaccine. At present, natural disease exists in some countries, especially those in Africa. The vaccineassociated paralytic poliomyelitis (VAPP) is an unwanted adverse event of vaccination. Recently, transition from the trivalent to bivalent oral poliovirus vaccine becomes a global public health manipulation.^{[1]} Thailand is a tropical country in Indochina that already implemented the transition (in April 2016).^{[2]} Of interest, the study on overall poliovirus shredding rate in random collected stool in Thailand showed similar observed rates prior and post transition (estimated 0.44%).^{[3]}
Here, the authors performed a mathematical model study to find the expected VAPP rate in Thailand. The primary included data for further analysis included: (a) frequencies of isolated vaccinerelated poliovirus^{[4]} and (b) the reported rate of VAPP in Thailand before transition of vaccine^{[5]} [Table 1]. First, the frequencies of isolated vaccinerelated polio virus strains were determined based on the available data.^{[4]} The mentioned primary data are used for construction of mathematical model based on path probability calculation. The path probability is the chance that an event will occur if the event occurs in that path. In the present model, a path is a polio virus strain (PV1, PV2, or PV3). The final rate is calculated using the following formula “VAPP rate due to a polio virus strain = frequency of that strain × rate of VAPP before transition.”  Table 1: Derive data according to mathematical modeling in the present study
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For pretransition, the expected VAPP rates due to PV1, PV2, and PV3 are equal to less than 0.00001650%, 0.00001650%, and 0.00000825%, respectively. For posttransition, the expected rates of VAPP due to PV1, PV2, and PV3 are less than 0.00000165%, 0%, and 0.00000165%, respectively. The overall expected VAPP rate is equal to less than 0.00000330%. There is no change of mathematical model derived overall VAPP but there is a change of the strain specific rate. Now, the surveillance for VAPP according to PV1 and PV2 is still necessary.
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Conflicts of interest
There are no conflicts of interest.
References   
1.  World Health Organization. Polio vaccines: WHO position paper, March 2016recommendations. Vaccine 2017;35:11979. 
2.  Bahl S, Hasman A, Eltayeb AO, James Noble D, Thapa A. The switch from trivalent to bivalent oral poliovirus vaccine in the SouthEast Asia region. J Infect Dis 2017;216(Suppl_1):S94S100. 
3.  Chansaenroj J, Chuchaona W, Thanusuwannasak T, DuangIn A, Puenpa J, Vutithanachot V, et al. Prevalence of poliovirus vaccine strains in randomized stool samples from 2010 to 2018: Encompassing transition from the trivalent to bivalent oral poliovirus vaccine. Virusdisease 2019;30:2016. 
4.  Kumthip K, Khamrin P, Maneekarn N. Detection of poliovirus infection in children with acute gastroenteritis in Chiang Mai, Thailand. J Med Virol 2017;89:77581. 
5.  Kijphati R, Pongsuwanna Y, Tungcharoensilp S, Onvimol N, Singchai P, Suwanpanyalert P. Situation of vaccineassociated paralytic poliomyelitis case in Thailand, 2001 2002. Bull Dep Med Sci 2004;46:2535. 
[Table 1]
