Sinovac - Study shows, Children aged 3-8 years old receive 2 doses of influenza vaccine for better protection

On October 12, 2023, the international journal Vaccines published online an article titled Immunogenicity and Safety of One versus Two Doses of Quadrivalent Inactivated Influenza Vaccine (IIV4) in Vaccine-Unprimed Children and One Dose of IIV4 inVaccine-Primed Children Aged 3-8 Years ('Immunogenicity and safety of quadrivalent influenza virus split vaccine in unvaccinated (1 dose) and vaccinated children aged 3-8 years after one and two doses respectively') research results.

This study supports the vaccination recommendation in the 'China Technical Guidelines for Influenza Vaccination' that children aged 3-8 years receive two doses of IIV4.

Influenza is an acute respiratory infectious disease caused by influenza viruses, which seriously endangers people's health. According to World Health Organization estimates, seasonal influenza infects as many as 1 billion people globally each year, accounting for approximately 15% of the world's population. It can cause 3 million to 5 million severe cases and 290,000 to 650,000 respiratory disease-related deaths every year. The influenza attack rate in children is about 20%-30%. In high epidemic seasons, the annual influenza infection rate in children can be as high as about 50%, which is higher than that in adults. Influenza vaccination is an effective means to prevent influenza and reduce the burden of influenza-related severe illness and death. The World Health Organization's position paper on influenza vaccines updated in May 2022 emphasized that vaccination can reduce the impact of severe influenza-related illness and death in high-risk groups, prevent influenza, and reduce transmission.

Although there is consensus on the importance of influenza vaccination in children, there are still differing views on the optimal dosing regimen for childhood influenza vaccination. The 'Technical Guidelines for Influenza Vaccination in China (2023-2024)' issued by the Chinese Center for Disease Control and Prevention recommends: For influenza virus split vaccines, children aged 6 months to 8 years old who receive the influenza vaccine for the first time should receive two doses, with an interval of 4 weeks; for children who have received one or more doses of influenza vaccine in 2021-2022 or previously, one dose is recommended. The American Academy of Pediatrics (AAP) recommends that for this group of children, children who have not received two doses of trivalent or quadrivalent influenza virus split vaccine before July 1, 2022, receive two doses of influenza vaccine.

In order to provide evidence support for the optimal influenza vaccine immunization strategy for children aged 3-8 years old, the Jiangsu Provincial Center for Disease Control and Prevention and SINOVAC conducted this study in 2021. This study is a randomized, open-label, parallel-controlled phase IV clinical study. A total of 600 subjects were included in the study, of which 400 subjects who had not been vaccinated or had received one dose of influenza vaccine were randomly divided into 2 groups in a ratio of 1:1, and a group of 200 subjects were randomly divided into 2 groups according to a ratio of 0,28 Two doses of IIV4 were administered during the daily immunization schedule, and another group of 200 subjects were vaccinated with one dose of IIV4. In addition, there was also a group of 200 subjects who had received two or more doses of influenza vaccine in the past, and the subjects in this group were vaccinated One dose of IIV4.

Both one-dose and two-dose IIV4 elicited strong immune responses to all four influenza strains in children aged 3 to 8 years who had not received or received one dose of influenza vaccine before.

The influenza hemagglutinin (HI) inhibitory antibody seroconversion rate of all subjects after vaccination ranged from 61.86% to 95.86%, and the seroprotection rates of influenza HI antibodies for the four types were all >70%, in line with the European Medicines Agency's regulations influenza vaccine standards.

Among children who had not previously been vaccinated or who had received one dose of influenza vaccine, the seroprotection rate after two doses of IIV4 was higher than the seroprotection rate after one dose of IIV4.

The seroprotection rate of two doses of IIV4 in children who had not received previous influenza vaccine or who had received one dose of influenza vaccine was comparable to the seroprotection rate of one dose of IIV4 in children who had received two or more previous doses of influenza vaccine.

Across all subjects, no vaccine-related serious adverse events were reported.

This study supports the recommendation in the Chinese Technical Guidelines for Influenza Vaccination to administer two doses of IIV4 to children aged 3-8 years who have not previously been vaccinated or have received one dose of influenza vaccine, and also to vaccinate children with SINOVAC Sinovac influenza vaccine provides more evidence of effectiveness and safety.

About SINOVAC

Sinovac Biotech Ltd. (SINOVAC) is China's leading biotech enterprise. With the mission of 'providing vaccines to eliminate diseases for humans', it is committed to the research of human vaccines and related products. Development, production and sales to provide services for global disease prevention and control.

The vaccines developed by SINOVAC mainly include vaccines against viral hepatitis, influenza, pneumonia, polio, chickenpox, mumps and other common infectious diseases, as well as vaccines against SARS, H5N1 avian influenza, H1N1 pandemic influenza, EV71 hand, foot and mouth disease, novel Vaccines for emerging and emerging infectious diseases such as coronavirus infections.

The company's current 4 vaccines have passed World Health Organization pre-certification (inactivated hepatitis A vaccine, Sabin strain inactivated polio vaccine, live attenuated chickenpox vaccine) or are included in the emergency use list (new coronavirus inactivated vaccine). The quality of the vaccines is The management system has been recognized by international organizations and multinational drug regulatory authorities.

SINOVAC is constantly exploring opportunities in the international market and has exported vaccines to dozens of countries and international organizations.

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