Reduction in COVID-19 Patients Requiring Mechanical Ventilation Following Implementation of a National COVID-19 Vaccination Program

Israel, December 2020-February 2021

Ehud Rinott; Ilan Youngster, MD; Yair E. Lewis, MD, PhD

Disclosures

Morbidity and Mortality Weekly Report. 2021;70(9):326-328. 

In This Article

Abstract and Introduction

Introduction

The availability of COVID-19 vaccines represents an opportunity to mitigate the effects of the global pandemic. Achieving high vaccination coverage through intensive vaccination campaigns has the potential to substantially reduce COVID-19–associated morbidity and mortality. Clinical trials have demonstrated the efficacy of COVID-19 vaccines in preventing mild and severe COVID-19 in a controlled setting. However, clinical trials are not designed to assess the population impact of vaccination in a real-world setting.[1,2] Israel initiated a national vaccination campaign using the Pfizer-BioNTech BNT162b2 (Pfizer-BioNTech) vaccine in December 2020, prioritizing persons aged >60 years, health care workers, and persons with underlying medical conditions. By February 2021, 2-dose vaccination coverage among persons aged ≥70 years was 84%. To assess the effect of COVID-19 vaccination on the occurrence of severe disease, an ecological study was conducted. Requiring mechanical ventilation was used as a proxy for severe COVID-19. The number of COVID-19 patients aged ≥70 years (who had the highest 2-dose vaccination coverage, 84.3%) requiring mechanical ventilation was compared with that of patients aged <50 years, who had the lowest 2-dose vaccination coverage (9.9%). Since implementation of the second dose of the vaccination campaign, the ratio of COVID-19 patients requiring mechanical ventilation aged ≥70 years to those aged <50 years has declined 67%, from 5.8:1 during October–December 2020 to 1.9:1 in February 2021. These findings provide preliminary evidence of the effectiveness of vaccines in preventing severe cases of COVID-19 at the national level in Israel. Receipt of COVID-19 vaccines by eligible persons can help limit spread of disease and potentially reduce the occurrence of severe disease.

The first case of COVID-19 in Israel, a country with a population of approximately 9 million, was reported in February 2020. As of February 9, 2021, approximately 700,000 cases and 5,200 deaths had been reported.[3] Nonpharmaceutical interventions have included three national stay-at-home orders, multiple rounds of school closures, restrictions on commercial activity and travel, and a mask mandate, among others. The most recent stay-at-home order was implemented on January 8, 2021, amid a nationwide surge in cases.[4] On December 20, 2020, Israel initiated a national vaccination program against COVID-19, using the Pfizer-BioNTech vaccine and prioritizing persons aged ≥60 years, health care workers, and persons with chronic conditions that increase risk for infection or severe disease.[5]

To assess the impact of COVID-19 vaccination on the occurrence of severe COVID-19 at the population level an ecological study was conducted using the number of COVID-19 patients requiring mechanical ventilation as a proxy for severe disease. The number of COVID-19 patients requiring mechanical ventilation aged ≥70 years, who had the highest 2-dose COVID-19 vaccination coverage, was compared with the number of those aged <50 years, who had the lowest 2-dose coverage. COVID-19 vaccine administration data during December 20, 2020–February 9, 2021, were obtained from publicly available Israel Ministry of Health data.[6] Vaccinated persons with missing age data were excluded from the analysis. Daily numbers of COVID-19 patients receiving mechanical ventilation between October 2, 2020, and February 9, 2021, (including during the second and third stay-at-home orders) were obtained from the Israel Ministry of Health COVID-19 dashboard using a publicly available repository.§ Vaccination status is not available for individual patients in this repository. Population data were drawn from the Israel Central Bureau of Statistics as of the end of 2019.

By February 9, 2021, a total of 3,606,858 persons had received the first vaccine dose, and among those, 2,223,176 (62%) had received the second dose. Two-dose COVID-19 vaccination coverage among persons aged ≥70 years, 60–69 years, 50–59 years, and <50 years was 84.3%, 69.0%, 50.2%, and 9.9%, respectively (Figure 1).

Figure 1.

First- and second-dose COVID-19 vaccination coverage* among persons aged <50 and ≥70 years† — Israel, December 20, 2020– February 9, 2021
*Dose 2 shaded areas include those who received dose 1.
Total population: 6.4 million (aged <50 years); 0.735 million (aged ≥70 years).

During October 2, 2020–February 9, 2021, the median daily numbers of COVID-19 patients aged <50 years and ≥70 years who required mechanical ventilation were 15 (range = 6–63) and 84 (range = 45–127), respectively. During October 8–December 30, 2020, the mean ratio of ventilated patients aged ≥70 years to those aged <50 years was 5.8:1 (99% confidence interval = 5.5–6.1; range = 4.2–8.5). During the last week of January 2021, although the average daily number of ventilated patients aged ≥70 years had begun to decline, the average daily number of ventilated patients aged <50 years was still increasing (Figure 2). By February 9, 2021, the 7-day rolling average number of ventilated patients aged ≥70 years was 109, and among those aged <50 years was 57.7 (ratio = 1.9:1), representing a 67% decrease in the ratio compared with that during October 8–December 30, 2020.

Figure 2.

Number and ratio of COVID-19 patients aged <50 and ≥70 years requiring mechanical ventilation — Israel, October 8, 2020– February 9, 2021

*These authors contributed equally to this report.
The dates of the three stay-at-home orders were March 12–April 19, 2020; September 18–October 18, 2020; and January 8–February 7, 2021.
§ https://github.com/dancarmoz/israel_moh_covid_dashboard_data

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