OK, but where are they going to trial their other options? Presumably not in China, where there is no virus.
A Chinese border city hit by a fresh outbreak of COVID-19 has begun a five-day drive to vaccinate its entire population of 300,000 people.
apnews.com
I don't see that it is possible to say a country the size and nature of China has "no" virus - otherwise this kind of news would not happen.
If China are saying they may need to give people a third shot to get optimal levels of protection, how the heck is that going to work in a region where countries like Argentine struggle to get even
one shot into people's arm? Both time and money are slipping away.
What is missing from this discussion is still the "new" factor of key variants spreading in
this region. All COVID vaccines have only been tested for a matter of months, not years, and mostly on strains that did not exist when they were deemed safe and X% effective. New studies on new variants take time and numbers even if there are a handful of "preliminary" studies. In Brazil Butantan found Sinovac only 73% effective against avoiding mild-severe illness - meaning it would not offer
health systems as much protection as say Pfizer, Sputnik or Astrozenaca since 27% of those vaccinated and then infected may still require hospitalisation to avoid death (based on the evolution of facts to date.) Now doubts around Sinopharm's effectiveness against avoiding serious illness in Peru also need to be examined.
Not even Sputnik V is free from this kind of issue nor any of the western counterparts. The looming doubt in the background to remain conscious of is that some coronaviruses just don't work with vaccines (e.g. common cold/ rhinovirus) and others (e.g. influenza) require new versions, and thus big logistics (e.g. time and money) ever year due to speed of mutation.
On the other hand, so far the only countries to have demonstrated a big downturn in cases, possibly due to having achieved massive vaccination levels of either first or second doses, are countries like UK, USA, Israel and UAE who mainly used Pfizer or AstraZeneca. However seasonality may still be a factor as people spend more time outdoors again - at the moment we just don't know for certain until their numbers pass the test of time. In the meantime the virus continues to mutate unevenly around the world.