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Friday, May 17, 2024

Foreign research finds Inactivated Vaccines give children more than 90% hospitalization protection against COVID-19 Immunogenicity increased 30-fold with booster dose

As schools around Thailand got back to normal and opened their doors to students learning on-site once again in mid-May, Centre of COVID-19 Situation Administration (CCSA) issued public health measures for both boarding schools and day schools to cope with a full timetable safely.

Students, teachers, and school employees must cooperate in strict compliance with Measure 6-6-7 for educational institutions. These include social distancing, wearing face masks, frequent ATK testing in case of symptoms or risks, and vaccination for children to build immunity and reduce the rate of infection. Students aged 12 to 17 are required to have a booster dose of vaccine through the institution’s system, while 5- to 11-year-olds should be vaccinated urgently at the discretion of the parents and their children. The latter group in particular, who have not previously received the vaccine, are more of a critical risk group to get infected by going to school. Between 22 April and 11 May 2022, Department of Health of the Ministry of Public Health found that the collective first dose vaccination rate of children aged 5 to 11 is 55.8%, when the second dose rate is only 22.1%. On top of this, the rate of non-vaccination is still 28.7%.

These numbers starkly show that there is a large population of children who have completely missed out on vaccination, from a number of different causes. The most pressing factor is parents’ concerns over choosing a vaccine for their children by themselves, whether it is a matter of side effects of vaccination on the children’s health both short-term and long-term, or the vaccine’s efficacy at preventing infection. Parents in this group of concern can then be hesitant about choosing a vaccine.

The latest research gives data about the effectiveness of “inactivated vaccines” for their recipients, particularly children. They have become another alternative of interest to parents. The research also indicated support for the fact that inactivated vaccines are certifiably safe for children, and that they have been approved for children on a broad basis. Inactivated vaccines for children is not a new concept, and inactivated vaccines have had a previous role to prevent children’s diseases such as polio and influenza.

It has been proven that they have protective efficacy with good safety profile, whether acute or chronic. As well as having been previously used for children, inactivated vaccines are still very popular among the group of users with special conditions such as pregnant women and the immuno-compromised, because there is no replicating virus component. These vaccines were the model to develop the current batch of inactivated vaccines to prevent COVID-19. Inactivated vaccines which have been approved for children in Thailand include Sinovac and Sinopharm for children aged 6 and above, while Sinovac has also been approved for children and young people in 14 countries such as Chile, Brazil, and Hong Kong. Over 260 million doses have now been administered to children worldwide.

Recently, SINOVAC Biotech Ltd. released research about the efficacy of inactivated vaccines for children under the heading “Safety and Cross-Reactive Immune Response Against the Omicron Variant of a Third Dose of CoronaVac®, and Immune Persistence of Primary Immunization in Healthy Children and Adolescents: Interim Results from a Double-Blind, Randomised, Placebo-Controlled Phase 2 Clinical Trial”.

In total, 346 children and adolescents between the ages of 3 and 17 received a CoronaVac® booster after 10 or 12 months following the second dose. Researchers tested all participants 28 days after their third shot and found more than a 30-fold increase in the level of neutralizing antibodies against the original strain of COVID-19.

This was a double-blind study conducted with randomised sampling and a placebo control group. The second phase of clinical trials discovered that the vaccine fostered pronounced effective safety among the sample group, while building immunity to stop the spread of COVID-19’s Omicron variant.

The result showed the adverse reactions were primarily mild and no severe adverse events were reported after receiving the booster dose. The seroconversion rate against the original strain and Omicron variant were 100% and above 90% respectively. The antibody levels against the original strain of COVID-19 were increased about 30-fold.

On the other hand, Chilean Real-World Studies have shown that the vaccine effectiveness for children and adolescents aged 6-16 with a complete primary immunization with CoronaVac® was 74.5%, 91.0%, and 93.8% for Covid-19, hospitalization, and ICU admission. During the Omicron outbreak, the vaccine effectiveness against hospitalization and preventing ICU were 64.6% and 69.0% respectively among children 3-5 years old.

Despite the fact that rates of COVID-19 infection may have a current downward trend after the first-wave spikes, coupled with the infection becoming less severe, the situation of infection among children after schools have reopened must still be closely monitored as most children infected with COVID-19 do not have severe symptoms or are completely asymptomatic. As a result, symptoms may take time to emerge and are a key factor in the spread of infection. Meanwhile the group of children with chronic personal conditions must be especially careful, as severe side effects may arise from infection. Apart from this, children previously infected with COVID-19 may have risk of Multisystem Inflammatory Syndrome in Children (MIS-C). This can be severe and have negative impacts on both the heart and the gastrointestinal tract. There is also the matter of Long COVID in children, about which there is no clear data. Vaccination to prevent COVID-19 can address these risk . Alongside the requirement to carefully monitor symptoms, parents must also choose a safe vaccine as the factor to most efficiently prevent infection, helping their children get back to school in their classrooms safely in the long-term.

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