The only thing that has been proven conclusively is that new variants spread more easily, but there is no conclusive evidence that they are becoming deadlier. By mutating, viruses want to get a competitive advantage to infect as many people as possible without killing the host.
New variants making the rounds mean new research studies need to confirm whether our current vaccines are still effective. I am confident the vaccines will more than likely still be effective, especially when it comes to minimising severe COVID-19 hospitalisations and deaths. But there could be a slight drop in effectiveness, as we saw with the other variants.
Vaccine effectiveness is a measure of how well a vaccine works in the real world and is measured by observing how well it works to protect communities as a whole. It differs from vaccine efficacy which is measured in a large trial under very specific conditions. Based on the effectiveness of the current COVID-19 vaccines, it does not mean that you will not get the virus at all.
There is a notion that only unvaccinated people drive the emergence of new variants. As long as vaccinated people can still become infected, this is not true. The virus replicates in both vaccinated and unvaccinated people, but there are different schools of thought on the topic.
For now, we have no idea how long the vaccine will be effective. Current studies show that antibodies start waning after four to six months but still remain at levels high enough to minimise severe COVID-19, hospitalisations and deaths. Importantly, vaccination also stimulates cell-mediated immunity, with T and B cells determining the duration of long-term immunity. For certain vaccines, T cells have been reported up to nine months after receiving the vaccine. All studies measuring antibodies and T cells are still ongoing, and only time will tell how long they last.