Modeling study evaluates the effectiveness of face masks before and after COVID-19 vaccination
Modeling study evaluates the effectiveness of face masks before and after COVID-19 vaccination

Modeling study evaluates the effectiveness of face masks before and after COVID-19 vaccination

Researchers and health officials have developed several pharmaceutical and non-pharmaceutical interventions to curb the ongoing coronavirus disease 2019 (COVID-19) pandemic. For example, wearing face masks has been one of the most effective non-pharmaceutical measures that have been adopted globally to prevent further spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and to protect individuals from get COVID-19.

Examination: Maintaining the use of face mask before and after achieving different COVID-19 vaccination coverage levels: a modeling study. Image credit: Mr. Tempter /


Early in the COVID-19 pandemic, most people in the United States wore face masks. However, researchers observed that this practice was eased since the spring of 2021, even though vaccination rates were below what has been projected to reach herd immunity thresholds.

In mid-May 2021, the U.S. Centers for Disease Control and Prevention (CDC) announced that vaccinated individuals were not required to wear face masks when indoors in public places such as restaurants. This caused both vaccinated and unvaccinated individuals to stop wearing face masks, which was quickly followed by a significant increase in COVID-19 cases due to the SARS-CoV-2 delta (B.1.617.2) and Omicron (B .1.1.529) variants.

This increase in COVID-19 cases quickly prompted local officials to reintroduce face mask requirements in Los Angeles County, California and Washington DC Although several studies have shown that face masks effectively prevent SARS-CoV-2 transmission, the use of face masks in 2021 lower than it was in 2020.

Around examination

Recently, researchers have addressed some important issues regarding the use of face masks, such as whether face masks should be worn in public indoor locations such as grocery stores and public transportation, and how long this practice should be maintained.

In this context, scientists have in a recent The Lancet Public Health study simulated different scenarios using face masks through a computational Monte Carlo simulation model representing the population of the United States and SARS-CoV-2 transmission. In addition, the researchers performed simulations to compare different scenarios, which included predictions of the results for people who wore a face mask and those who did not wear a face mask before the goal of vaccination coverage of 70-90% of the population was achieved.

Survey results

The current study emphasized that COVID-19 vaccination alone is not enough to deal with the pandemic. Several interventions were required to prevent transmission of SARS-CoV-2, death and suffering.

Since each intervention, including the frequent use of disinfectants, face masks and social restrictions, is associated with different constraints, a combination effect of multiple interventions can positively enhance their effect and combat the pandemic.

The authors provided strong evidence showing that the use of face masks is an effective and cost-effective method of dealing with the COVID-19 pandemic. The current study also revealed that face masks must be worn continuously, even after reaching specific vaccination coverage levels to achieve herd immunity.

Continuous use of face masks is important as virus transmission does not stop immediately when the vaccination threshold is reached. In fact, face masks appear to provide additional prevention until the transfer gradually subsides after two to ten weeks.

The decrease in vaccine efficacy due to the emergence of new SARS-CoV-2 variants and declining immune response induced by vaccination or natural infection has increased the value of wearing face masks.

The researchers note that it is not realistic to assume that all individuals with COVID-19 will remain isolated throughout their infected phase. This is because many people are not tested for SARS-CoV-2 infection, asymptomatically infected individuals may transmit the infection unintentionally, or some patients may be tempted not to remain isolated throughout the infected phase. This situation further underscores the importance of using face masks to control the pandemic.

The authors recommend that all persons continue to wear face masks, regardless of their age group or profession. When the efficiency of the face mask was increased by 10%, a relative reduction of 17-20% of the COVID-19 cases was observed. In addition, a significant reduction in hospital admissions and deaths due to SARS-CoV-2 infection was reported.

Study takeaways

Although the current model is based in the United States, these results may be similar to scenarios in other countries. Moreover, all models represent a simplified version of real conditions and cannot account for all possible outcomes.

In case there is a lack of effective face masks, such as N95 masks, it is better to wear a regular fabric mask than not to wear one, as people with COVID-19 are less likely to spread the disease when wearing face masks. Together, the researchers suggest the continuous use of face masks for two to ten weeks in addition to obtaining specific vaccination coverage to reduce residual SAR-CoV-2 transmission.

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