PT - JOURNAL ARTICLE ED - , TI - WHO adds Janssen vaccine to list of safe and effective emergency tools against COVID-19 DP - 2021 Apr 01 TA - Saudi Medical Journal PG - 463--464 VI - 42 IP - 4 4099 - http://smj.org.sa/content/42/4/463.short 4100 - http://smj.org.sa/content/42/4/463.full SO - Saudi Med J2021 Apr 01; 42