Because ADE of infection contributes to the pathogenesis of some viruses, such as dengue virus and feline coronavirus, it is important to evaluate the precise mechanism of ADE and its contribution to the pathogenesis of SARS-CoV-2. Antibody-dependent enhancement (ADE) of infection is an alternative mechanism of infection for viruses to infect immune cells that is mediated by antibodies and IgG receptors (FcγRs). IMPORTANCE Viruses infect cells mainly via specific receptors at the cell surface.
While the origin of the outbreak cannot be conclusively determined without additional evidence, there are very plausible alternatives to the laboratory accident hypothesis, diminishing the relevance of the 1977 experience to the modern GOF debate. Based on available evidence, the 1977 strain was indeed too closely matched to decades-old strains to likely be a natural occurrence.
Given the importance of this historical epidemic to ongoing policy debates, we revisit the evidence that the 1977 epidemic was not natural and examine three potential origins: a laboratory accident, a live-vaccine trial escape, or deliberate release as a biological weapon.
There is now a moratorium in the United States on funding GOF research while the benefits and risks, including the potential for accident, are analyzed. While there are several hypotheses that could explain its origin, the possibility that the 1977 epidemic resulted from a laboratory accident has recently gained popularity in discussions about the biosafety risks of gain-of-function (GOF) influenza virus research, as an argument for why this research should not be performed. The 1977-1978 influenza epidemic was probably not a natural event, as the genetic sequence of the virus was nearly identical to the sequences of decades-old strains. Our results demonstrate that there is a significant inverse correlation between mumps titers from MMR II and COVID-19 severity. Within the MMR II group, mumps titers of 134 to 300 arbitrary units (AU)/ml ( n = 8) were found only in those who were functionally immune or asymptomatic all with mild symptoms had mumps titers below 134 AU/ml ( n = 17) all with moderate symptoms had mumps titers below 75 AU/ml ( n = 11) all who had been hospitalized and had required oxygen had mumps titers below 32 AU/ml ( n = 5). There were no significant correlations between mumps titers and severity in the comparison group, between mumps titers and age in the MMR II group, or between severity and measles or rubella titers in either group. There was a significant inverse correlation ( r s = −0.71, P < 0.001) between mumps virus titers (mumps titers) and COVID-19 severity within the MMR II group. The MMR II group consisted of 50 subjects who would primarily have MMR antibodies from the MMR II vaccine, and a comparison group of 30 subjects consisted of those who would primarily have MMR antibodies from sources other than MMR II, including prior measles, mumps, and/or rubella illnesses. We divided 80 subjects into two groups, comparing MMR titers to recent COVID-19 severity levels. Our aim was to determine whether any MMR IgG titers are inversely correlated with severity in recovered COVID-19 patients previously vaccinated with MMR II.
The measles-mumps-rubella (MMR) vaccine has been theorized to provide protection against coronavirus disease 2019 (COVID-19).