The advantage of live vaccines
The result is a virus that is completely identical to the normal Sars-CoV-2 from the outside, but whose RNA is less stable and is broken down more quickly. As a result, the virus is contagious and triggers exactly the same antibody response as the original – but it multiplies much more poorly. The hamsters used in the study showed hardly any symptoms from the virus despite being infected and quickly got rid of the infection, the team reports. At the same time, it found signs of good activation of the immune system; in addition to IgA, B and T cells were also more strongly activated. »Live vaccines are known to activate very robust and long-lasting immunity. We know that from the measles, rubella or yellow fever vaccinations, for example.” writes the virologist Leif-Erik Sander from the Charité, who is not involved in the work, on Twitter.
The working group checked the success of the vaccination by infecting the vaccinated hamsters with normal Sars-CoV-2. While all three vaccines used only made the infection milder after one dose, the results of the booster vaccination trials suggest that sCPD9 as a booster could produce sterile immunity. In addition, the live vaccine better protected the animals’ lungs from inflammation and tissue damage.
The experiments indicate that the live-attenuated vaccine also improves protection against immune escape variants. Unlike the other vaccines, sCPD9 contains the whole virus, so the immune response is not directed exclusively at the highly variable spike protein. A double dose of the nasal spray vaccine gives the hamsters a “significant ability to neutralize this special variant of Sars-CoV-2,” the team writes about the Omicron experiments.
However, until the vaccine is used in humans, According to Wyler, it will probably take at least 18 months. Last but not least, such a vaccine must be tested very carefully for possible safety problems – an active virus is administered in the immediate vicinity of the brain. It remains to be seen whether the vaccine also works so well in humans. Another hurdle is the existing vaccines – a new preparation not only has to protect, but also protect demonstrably better than this.