Modeling the Impact of COVID-19 Vaccination in Lebanon: A Call to Speed-Up Vaccine Roll Out

Abstract

Four months into the SARS-CoV-2 vaccination campaign, only 10.7% of the Lebanese population have received at least one dose, raising serious concerns over the speed of vaccine roll-out and its impact in the event of a future surge. Using mathematical modeling, we assessed the short-term impact of various vaccine roll-out scenarios on SARS-CoV-2 epidemic course in Lebanon. At current population immunity levels, estimated by the model at 40% on 15 April 2021, a large epidemic wave is predicted if all social distancing restrictions are gradually eased and variants of concern are introduced. Reaching 80% vaccine coverage by the end of 2021 will flatten the epidemic curve and will result in a 37% and 34% decrease in the peak daily numbers of severe/critical disease cases and deaths, respectively; while reaching intermediate coverage of 40% will result in only a 10-11% decrease in each. Reaching 80% vaccine coverage by August would prevent twice as many severe/critical disease cases and deaths than if it were reached by December. Easing restrictions over a longer duration resulted in more favorable vaccination impact. In conclusion, for vaccination to have impact in the short-term, scale-up has to be rapid and reach high coverage (at least 70%), while sustaining social distancing measures during roll-out. At current vaccination pace, this is unlikely to be achieved. Concerted efforts need to be made to overcome local challenges and substantially scale up vaccination to avoid a surge that the country, with its multiple crises and limited health-care capacity, is largely unprepared for.

Keywords: COVID-19; Lebanon; SARS-CoV-2; coronavirus; epidemiology; mathematical model; vaccine.

Figure 1

Impact of SARS-CoV-2 vaccination on number of (A) new infections, (B) new severe and critical disease cases, and (C) new deaths in Lebanon. The vaccine is introduced on 14 February 2021 and vaccine coverage is scaled up to reach 40% (red curve) or 80% (yellow curve) by 31 December 2021. The simulations assume R₀ of 1.2 from 1 January 2021 to 15 April 2021 when it starts to increase with gradual easing of restrictions to reach 6.0 after four months.

Figure 2

Impact of various levels of vaccine coverage reached by 31 December 2021 on the cumulative number of averted (A) severe and critical disease cases and (B) deaths from 14 February 2021 (date of vaccine introduction) to 31 December 2021. The scenarios assume gradual easing of all restrictions over four months starting 15 April 2021.

Figure 3

Impact of vaccine scale-up duration to reach 80% coverage by 31 December 2021 on the cumulative number of averted (A) severe and critical disease cases and (B) deaths from 14 February 2021 (date of vaccine introduction) to 31 December 2021. The scenarios assume gradual easing of all restrictions over four months starting 15 April 2021.

Figure 4

Impact of the duration of easing social and physical distancing restrictions on the cumulative number of averted (A) severe and critical disease cases and (B) deaths from 14 February 2021 (date of vaccine introduction) to 31 December 2021. The scenarios assume gradual easing of all restrictions over four months starting 15 April 2021 and reaching 80% vaccine coverage by 31 December 2021.