A new study found that extending the vaccination interval between coronavirus vaccine doses may provide a higher level of protection against Omicron sub-variants and comes as some countries are recommending a fourth booster shot to curb the rise in infections.

Researchers published the study in The New England Journal of Medicine earlier this month and were led by an academician of the Chinese Academy of Sciences (CAS), Gao Fu. He is also the head of the Chinese Center for Disease Control and Prevention (CDC).

Vaccines Against Omicron Sub-variants

The team assessed the neutralization antibody levels against the SARS-CoV-2 original and Omicron sub-variants, including BA.4 and BA.5, in blood samples obtained from vaccine takers. The patients involved had received three doses of China-made inactivated vaccines, three-shot protein-subunit vaccine ZF2001, or two doses of inactivated vaccines booster by ZF2001.

The results of the study showed that in each vaccine group, the neutralizing antibody levels against all the tested Omicron sub-variants were significantly lower than the levels against the original strain of the virus. This indicated that the sub-variants had an ability to evade immune protection, as per CGTN.

However, researchers found that for the ZF2001, the neutralizing antibody levels rose with the increasing interval between the second and third doses, especially against the Omicron sub-variants.

Read Also: French-Based Pharmaceutical Requests FDA for Approval of Over-The-Counter Abortion Pill in the US

The neutralizing antibody levels of vaccine takers who had an interval of four to six months between their second and third doses were higher by nearly a factor of 10 against the original strain and by a factor of roughly 30 against all Omicron sub-variants compared to those who had a one-month interval between vaccine doses.

According to News Medical, another group of researchers also studied the efficacy of the fourth vaccine dose against coronavirus disease among long-term care residents. The study was published in The British Medical Journal (BMJ).

Coronavirus Surge

Health experts noted that long-term care (LTC) residents are at an increased risk of infection with severe respiratory syndrome coronavirus 2 (SARS-CoV-2) and severe outcomes. Researchers estimated the marginal effectiveness of the fourth vaccine dose compared to a third dose.

The authors implemented a test-negative design and determined marginal effectiveness (fourth vs. third) and vaccine effectiveness *of the fourth dose) among residents across 626 licensed LTC homes in Ontario. The patients in the study were excluded if they received the second booster before Dec. 30, 2021, or tested positive for the coronavirus in the past 30 days.

These studies come as there are growing concerns of complacency among West Australians towards a fourth COVID-19 vaccination as previous boosters wane. The Pharmacy Guild of Australia, which represents 550 pharmacies across WA, said that it was particularly important for the one in five people across the state who have not yet received their third vaccine doses to protect themselves and their loved ones.

The group recommended that all adults aged 50 and older get their fourth dose, although this is not required by law. Furthermore, a winter booster is also available for people aged between 30 and 49 years old, ABC reported

Related Article: Omicron Subvariant Surge Prompts Chinese Authorities To Mull a Potential Second Major Lockdown