More than 200 vaccine candidates for COVID-19 are currently in development, employing a wide range of vaccine technologies. Findings from a new study demonstrate that a measles-based vector vaccine may be effective against COVID-19.
Measles is a highly contagious disease caused by the measles virus. The current measles vaccine, which was developed in the early 1960s, is based on an attenuated, live virus. It has been one of the safest and most successful vaccines ever used in children and is often delivered as part of a triple vaccine against measles, mumps, and rubella, commonly referred to as the MMR vaccine.
Vector vaccines use an altered version of a virus to deliver instructions, in the form of genetic material, to induce antibody production against a different virus. Vector vaccines have been used safely against a variety of viral illnesses, including influenza, hepatitis, and others.
COVID-19 is caused by the SARS-CoV-2 virus. The primary antigenic component – the part of the virus that provokes an immune response – is a spiky protein on the surface of the vaccine (aptly named a spike protein) that attaches to receptors on mammalian cells. Prior to its attachment, it is referred to as the prefusion spike protein.
The authors of the study developed several measles virus vector vaccines carrying genetic material for different forms of the SARS-CoV-2 and tested them in several rodent models. They found that vaccines carrying genetic information for the prefusion spike protein induced neutralizing antibody levels higher than those present in convalescent plasma of patients recovered from COVID-19, as well as a robust T cell immune response, even among animals previously vaccinated against measles. In fact, the prefusion spike protein vector vaccine provided complete protection against SARS-CoV-2 challenge and associated respiratory illness – in a single immunization.
These findings suggest that the measles vaccine is an excellent vehicle for delivering protection against the SARS-CoV-2 virus. The authors posited that their vector-based prefusion spike protein vaccine could be incorporated into the current MMR vaccine as a quadruple protection against multiple pathogens.
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