A common concern after recovering from COVID-19 is the potential for reinfection from personal items like a toothbrush. This article clarifies the science behind viral survival on surfaces, the conditions of a toothbrush, and the actual risk of reinfection.
How Viruses Persist on Surfaces
SARS-CoV-2, the virus causing COVID-19, can survive on inanimate surfaces for varying periods. Its viability depends on factors like surface type, temperature, humidity, and initial viral load. The virus persists longer on non-porous materials such as plastic and stainless steel than on porous surfaces like cardboard. Studies indicate infectious SARS-CoV-2 can remain detectable on non-porous surfaces for up to 72 hours, sometimes longer. However, its ability to cause infection significantly decreases over time, with higher temperatures and humidity leading to faster decay.
The Toothbrush Environment
A toothbrush presents a unique environment for viral persistence. They typically feature plastic handles and nylon bristles, which are non-porous or semi-porous. Moisture from brushing and the bathroom environment can influence viral survival. While viral particles may be present after use by an infected individual, conditions are not ideal for long-term infectious virus survival. Bristles are exposed to air, promoting drying, and regular rinsing removes debris and some viral load, causing any viable SARS-CoV-2 concentration to likely diminish rapidly.
Reinfection Risk
Reinfection from one’s own toothbrush after recovering from COVID-19 is highly unlikely. After SARS-CoV-2 infection, the immune system develops antibodies and memory cells, providing protection against subsequent infections and helping prevent immediate reinfection or leading to a milder illness if reinfection occurs. It is important to distinguish between detecting viral RNA and the presence of live, infectious virus. PCR tests detect RNA fragments, which can persist for weeks after an individual is no longer infectious. However, RNA presence does not mean viable, replication-competent virus is capable of causing new infection, and any viral load transferred from a toothbrush would likely be extremely low and insufficient to overcome existing immunity.
Practical Considerations
Given the low risk of reinfection from one’s own toothbrush after recovering from COVID-19, strict measures are not necessary. However, simple precautionary actions can offer peace of mind. Replacing your toothbrush after recovering from an illness is a common recommendation, as germs can linger on bristles, and this low-cost measure can reduce concerns about residual viral particles. Alternatively, thoroughly rinsing your toothbrush with tap water after use and allowing it to air dry upright is helpful. Soaking bristles in an antimicrobial mouthwash or hydrogen peroxide solution for a few minutes is also suggested for disinfection, and these steps are primarily precautionary and align with general good oral hygiene practices.