Smaller dose, improved immunity, proves study
Phuket health officials will use only 20% of the standard vaccine dose of AstraZeneca for the third-dose ‘booster shots’ and will administer the vaccine doses as subdermal injections, not intramuscular injections, to boost the recipient’s immunity.
The move follows a study conducted by medical officers at Vachira Phuket Hospital, hospital director Dr Chalermpong Sukontapol explained at a press conference at the hospital on Sept 15.
Joining the conference were the hospital’s Epidemiologist, Dr Withita Jaeng-iam, along with DEPA Phuket office Manager Pracha Asawathira and Phuket Tourist Association President Bhummikitti Ruktaengam.
“The team led by Dr Withita and Dr Suphalak Laongpetch initiated this research to find an alternative way to provide the third dose of vaccine in Phuket, and Thailand,” Dr Chalermpong said.
Dr Withita explained, “In this research, we had 242 participants who were 18-60 years old and we divided them into two groups. For the first group, of 120 participants, we injected 0.5ml of vaccine into their muscle [Intramuscular], which is normal for COVID-19 vaccine injection.
“For another 122 participants, we injected 0.1ml of vaccine under their skin [subcutaneous],” she said.
“The study found that participants who received the subcutaneous injection with 0.1ml of vaccine developed a slightly higher rate of immunity than the other group of participants,” Dr Withita explained.
“Participants who received subcutaneous injections had approximately 17,662.3 AU/ml, while participants who received intramuscular injections had 17,214.1 AU/ml. Both groups had a higher rate of immunity than the minimum threshold or 840 AU/ml.
“Additionally, participants who received subcutaneous injections had less side effects than the other group. Seventy of them had a fever or headache, while the number went up to 98 in the other group,” she said.
“The subcutaneous injection causes more irritation and redness at the injected area, it is not worrying,” she added.
“We will start providing the third dose of vaccine by subcutaneous injection to 200,000 people who received two doses of Sinovac,” Dr Withita said.
“To return to normal life, the third dose of vaccine is very necessary, and in the situation that we have limited doses of vaccine, the subcutaneous injection using less amount of vaccine helps us achieve that goal faster,” she said.
“This may be an important method to solve shortages of vaccine doses in many countries while the Delta variant is spreading,” Dr Withita concluded.