Journal Article

COVID-19 vaccine effectiveness against severe COVID-19 requiring oxygen therapy, invasive mechanical ventilation, and death in Japan: A multicenter case-control study (MOTIVATE study)

Yamaguchi, Asase, Inoue, Takeshi, Miwa, Maki, Matsunaga, Maiko, Shimizu, Keiki, Yamamoto, Kei, Sugita, Manabu, Okochi, Yasumi, Higaki, Taiki, Atagi, Kazuaki, Nakanishi, Asuka, Fujita, Yasuo, Oba, Kunihiro, Takeda, Shinhiro, Stucky, Ashley, Asakura, Takanori, Hashimoto, Satoru, Kato, Hideaki, Tochitani, Kentaro, Rinka, Hiroshi, Arashiro, Takeshi, Ogata, Yoshitaka, Fujitani, Shigeki, Nakagawa, Hidenori, Mizuno, Keiko, Nakamura, Akira, Nakayama, Sohei, Kobayashi, Mieko, Uchikura, Toshio, Ariyoshi, Koya, Motoda, Kentaro, Shimada-Sammori, Kaoru, Arima, Yuzo, Nakano, Yoshio, Fujimi, Satoshi, Hibberd, Martin, Suzuki, Motoi, Taniyama, Daisuke, Tsukahara, Maki, Asami, Takahiro, Kikuchi, Hitoshi, Takamatsu, Junpei, Suzuki, Tadaki, Smith, Chris, Yoshida, Toru, Nishida, Yusuke, Oka, Hideaki, Tanaka, Katsushi, Doi, Kent, Aono, Hiromi, Tsutsumi, Takeya, Ueda, Akihiro, Takeda, Saki, Jinta, Torahiko, Okugawa, Shu, Fujino, Yuji, Iwasawa, Takamasa, Hamaguchi, Masanari, Kanbe, Fumiko, Oyama, Keisuke, Kanai, Masayuki

2024

Overview

•Assessing vaccine effectiveness (VE) became challenging due to incidental infection.•A case-control study in 24 hospitals during Delta and Omicron with various outcomes.•Multiple outcomes with high protection of 2 doses for Delta and 3 doses for Omicron.•There was a trend towards higher VE for more severe and specific disease outcomes.•Importance of severe/specific outcomes to accurately show VE against severe disease. Since the SARS-CoV-2 Omicron variant became dominant, assessing COVID-19 vaccine effectiveness (VE) against severe disease using hospitalization as an outcome became more challenging due to incidental infections via admission screening and variable admission criteria, resulting in a wide range of estimates. To address this, the World Health Organization (WHO) guidance recommends the use of outcomes that are more specific to severe pneumonia such as oxygen use and mechanical ventilation. A case-control study was conducted in 24 hospitals in Japan for the Delta-dominant period (August-November 2021; “Delta”) and early Omicron (BA.1/BA.2)-dominant period (January-June 2022; “Omicron”). Detailed chart review/interviews were conducted in January-May 2023. VE was measured using various outcomes including disease requiring oxygen therapy, disease requiring invasive mechanical ventilation (IMV), death, outcome restricting to “true” severe COVID-19 (where oxygen requirement is due to COVID-19 rather than another condition(s)), and progression from oxygen use to IMV or death among COVID-19 patients. The analysis included 2125 individuals with respiratory failure (1608 cases [75.7%]; 99.2% of vaccinees received mRNA vaccines). During Delta, 2 doses provided high protection for up to 6 months (oxygen requirement: 95.2% [95% CI:88.7–98.0%] [restricted to “true” severe COVID-19: 95.5% {89.3–98.1%}]; IMV: 99.6% [97.3–99.9%]; fatal: 98.6% [92.3–99.7%]). During Omicron, 3 doses provided high protection for up to 6 months (oxygen requirement: 85.5% [68.8–93.3%] [“true” severe COVID-19: 88.1% {73.6–94.7%}]; IMV: 97.9% [85.9–99.7%]; fatal: 99.6% [95.2–99.97]). There was a trend towards higher VE for more severe and specific outcomes. Multiple outcomes pointed towards high protection of 2 doses during Delta and 3 doses during Omicron. These results demonstrate the importance of using severe and specific outcomes to accurately measure VE against severe COVID-19, as recommended in WHO guidance in settings of intense transmission as seen during Omicron.

• Publisher: Elsevier Ltd,Elsevier Limited
• Subject: Allergy and Immunology / Case studies / Case-Control Studies / Case-control study / Coronavirus disease (COVID-19) / COVID-19 / COVID-19 - prevention & control / COVID-19 infection / COVID-19 Vaccines / Death / Disease / disease severity / Effectiveness / Estimates / Hospitalization / Hospitals / Humans / Infections / Japan / Japan - epidemiology / Mechanical ventilation / Mortality / mRNA / Oxygen / Oxygen - therapeutic use / Oxygen requirement / Oxygen therapy / Pneumonia / Respiration, Artificial / Respiratory failure / SARS-CoV-2 / SARS-CoV-2 variants / Severe acute respiratory syndrome coronavirus 2 / Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) / therapeutics / Vaccine effectiveness / Vaccine Efficacy / Vaccines / Ventilation / Ventilators / World Health Organization