Real-World Effectiveness of Mix-and-Match Vaccine Regimens against SARS-CoV-2 Delta Variant in Thailand: A Nationwide Test-Negative Matched Case-Control Study

Rapeepong Suphanchaimat; Natthaprang Nittayasoot; Chuleeporn Jiraphongsa; Panithee Thammawijaya; Punsapach Bumrungwong; Atthavit Tulyathan; Nontawit Cheewaruangroj; Chakkarat Pittayawonganon; Piyanit Tharmaphornpilas

doi:10.3390/vaccines10071080

Real-World Effectiveness of Mix-and-Match Vaccine Regimens against SARS-CoV-2 Delta Variant in Thailand: A Nationwide Test-Negative Matched Case-Control Study

Vaccines (Basel). 2022 Jul 5;10(7):1080. doi: 10.3390/vaccines10071080.

Authors

Rapeepong Suphanchaimat^{1

2}, Natthaprang Nittayasoot¹, Chuleeporn Jiraphongsa¹, Panithee Thammawijaya¹, Punsapach Bumrungwong³, Atthavit Tulyathan³, Nontawit Cheewaruangroj³, Chakkarat Pittayawonganon¹, Piyanit Tharmaphornpilas¹

Affiliations

¹ Division of Epidemiology, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand.
² International Health Policy Program, Ministry of Public Health, Nonthaburi 11000, Thailand.
³ Government Big Data Institute, Bangkok 10900, Thailand.

Abstract

The objective of this study is to explore the real-world effectiveness of various vaccine regimens to tackle the epidemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant in Thailand during September-December 2021. We applied a test-negative case control study, using nationwide records of people tested for SARS-CoV-2. Each case was matched with two controls with respect to age, detection date, and specimen collection site. A conditional logistic regression was performed. Results were presented in the form vaccine effectiveness (VE) and 95% confidence interval. A total of 1,460,458 observations were analyzed. Overall, the two-dose heterologous prime-boost, ChAdOx1 + BNT162b2 and CoronaVac + BNT162b2, manifested the largest protection level (79.9% (74.0-84.5%) and 74.7% (62.8-82.8%)) and remained stable over the whole study course. The three-dose schedules (CoronaVac + CoronaVac + ChAdOx1, and CoronaVac + CoronaVac + BNT162b2) expressed very high degree of VE estimate (above 80.0% at any time interval). Concerning severe infection, almost all regimens displayed very high VE estimate. For the two-dose schedules, heterologous prime-boost regimens seemed to have slightly better protection for severe infection relative to homologous regimens. Campaigns to expedite the rollout of third-dose booster shot should be carried out. Heterologous prime-boost regimens should be considered as an option to enhance protection for the entire population.

Keywords: COVID-19; Delta variant; SARS-CoV-2; Thailand; vaccine effectiveness.

Grants and funding

The funding for field investigation was from the DDC core resources. The publication fee was supported by the Thailand MOPH–U.S. CDC Coordinating Unit.