As early as May 2021, researchers from Massachusetts Institute of Technology published study findings in the peer reviewed Journal of Mechanics and Physics of Solids claiming that vibration frequencies similar to that used in medical ultrasound diagnostics could literally cause the virus to disintegrate into pieces, hence inhibiting its replication.
The process of using ultrasound to inhibit the novel coronavirus is almost similar to a process called cell sonification in which cells are subjected to high frequency sounds to literally break them open.
The study findings were published on a preprint server and are currently being peer reviewed.
The development of effective virus inactivation methods is of great importance to control their SARS-CoV-2 spread(Patterson et al., 2020; Rabenau et al., 2005; Darnell et al., 2004). This study investigated the effect of low-intensity US on the infectivity SARS-CoV-2 virus.
Wierzbicki et al, in 2021, proposed the possibility of acoustic waves at the US frequency being able to damage and consequently neutralize the SARS-CoV-2 virus (Wierzbicki et al., 2021). The study carried out was theoretical. The authors used finite element modeling and simulated the vibration interaction caused by ultrasound resonance with the virus.
The work did not consider the propagation medium, and the authors found high frequencies between 100 and 500 MHz as possible resonance points of the virus carapace and its t-spike proteins. In a second work, Wierzbicki and Bai, in 2022, carried out a new theoretical study suggesting that frequencies, lower between 1 and 20 MHz, can also damage the a-helices and tropocollagen molecules of the SARS-CoV-2 spikes structures, consequently neutralizing the virus (Wierzbicki and Bai, 2022).
Frequencies of this magnitude would allow the use of US equipment for everyday use in medicine, properly regulated and safe for human use, in neutralizing SARS-CoV-2. Indeed, using US devices from medical diagnostics, we experimentally validate that lower frequencies can inhibit the infectivity of SARS- CoV-2.
Interestingly, our results indicate a specific frequency rate of US exposition in an aqueous culture medium. We showed that 5-10 MHz was the most effective in reducing the SARS-CoV-2 viable particles, including the SARS- CoV-2 strains, gamma, and delta, compared with other used frequencies.
Of note, Soto-Torres et al, in 2021 showed no significant differences in abnormal fetal US and Doppler findings observed between pregnant women who were positive for SARS‐CoV‐2 and controls that indicated equipment safety in humans (Soto-Torres et al., 2021).
The increase in temperature is related to the US exposition and elevated temperature inhibits SARS-CoV-2 replication (Ghoshal et al., 2011; Herder et al., 2021). We did not observe differences in the temperature of the culture medium during the US exposition. This result supports the specific virucidal effect of US treatment.
Further testing, using US-exposition to determine the microscopy-affected virus structure and different time points may help clarify the mechanisms involved, develop the optimal time for inactivation of SARS-CoV-2, and perform in vivo experiments with preclinical models.