Is the HPV vaccine safe? BMJ published the results of follow-up visits for 440,000 girls in Asia

Cervical cancer is one of the most common cancers in women 40 years old.
2020, more than 600,000 women worldwide will be newly diagnosed with cervical cancer, and more than 340,000 will be killed by cervical cancer, according to the latest figures from the World Health Organization's International Agency for Research on Cancer (IARC).
Although HPV vaccines have been widely recommended worldwide and national HPV vaccination programmes for girls have been launched in 124 countries worldwide by 2019, concerns about the safety of HPV vaccines persist and are one reason why some people are hesitant to vaccinate.
the timing of national immunization programmes, most of the current research evidence comes from Western countries.
recently, a study published in the British Medical Journal from South Korea assessed the link between HPV vaccination and adverse events among 440,000 adolescent girls, adding important evidence to the safety of HPV vaccine in Asian populations.
as part of its national immunization program, the CDC has been vaccinating girls ages 12-13 against two doses of two- or four-price HPV since June 2016.
in the first year of the programme, coverage of the first dose of HPV vaccine was 61.5 per cent among girls of appropriate age, which had increased to 87.2 per cent by 2018.
the study, based on the Korea Immunization Registration System information and the Korea National Health Information Database, covered national data from January 2017 to December 2019.
In order to better control the basic differences between vaccinated and non-vaccinated individuals, the team chose to compare the health status of hpV-vaccinated populations with data on people vaccinated against the B-brain and b-white vaccines, which have been shown to be safe and recommended for use in the same population in South Korea.
study excluded girls who were vaccinated against both secondary and four-price HPV vaccines, as well as those diagnosed with malignant, congenital or neonatal diseases.
study eventually included 441,399 girls aged 11-14 who had been vaccinated in 2017, of whom 382,020 had been vaccinated against HPV, involving about 500,000 doses of HPV, while 59,379 had not been vaccinated against HPV.
safety assessment focuses on 33 pre-defined adverse events, including endocrine diseases such as thyroid abnormalities, diabetes, Crohn's disease, ulcerative colitis, pancreatitis, stomach ulcers and other digestive disorders, Reynolds syndrome, venous thromboembolism, vasculitis, hypertension and other cardiovascular diseases, as well as musculoskeletal, blood, skin and nervous system problems.
During follow-up, these serious adverse events were not found to be associated with HPV vaccination compared to HPV vaccinators, except for a slight 11% increase in migraine risk in HPV vaccinators (1235.0 cases/100,000 people - year vs 920.9 cases / 100,000 people - year).
to further reduce the impact of confuse factors, the team conducted a secondary analysis of girls who were vaccinated against HPV and had serious adverse events.
data controls of one year (365 days) after HPV vaccination and 466-730 days after vaccination showed that migraines were more likely to occur one year after vaccination, and that there was no association between HPV vaccination and severe adverse events, including migraines.
In a follow-up discussion, the team noted that hormonal changes and menstruation were common risk factors for migraines, and that girls vaccinated against HPV were more likely to have menstrual-related migraines, taking into account the average age difference between the HPV vaccine group (12.42 years) and other vaccine groups (11.84 years), as well as the average age of Korean girls at the beginning of the wave (12.7 years).
sensitivity analysis of these studies also supports the increased effect of age on migraines over time.
addition, the results were consistent for different follow-up periods (90 days, 180 days and 2 years) and for different HPV vaccine subsypes.
Combined with these data, the team said that data from more than 50 doses of HPV vaccine, data from different vaccinators, and comparison data from different time periods of adverse event inoculations themselves, found no evidence to support the link between HPV vaccination and 33 serious adverse events, taking into account the pathophysiological characteristics of migraines and vaccination age, and should be carefully explained.
overall, the results in Korean girls are consistent with evidence from Western populations that supports the safety of the HPV vaccine.
: Yoon Dongwon, Lee Ji-Ho, Lee Hyesung, Shin Ju-Young. (2021). Association between human papillomavirus vaccination and serious adverse events in South Korean adolescent girls: nationwide cohort study. BMJ, DOI: Latest global cancer data: Cancer burden rises to 19.3 million new cases and 10.0 million cancer deaths in 2020. Retrieved Nov 16 ,2020,from