It's really important to check sources. What Reuters isn't sharing is that they're quoting YNet. No one in this country takes that paper seriously. It's literally a garbage tabloid. They literally publish articles for the sake of publishing article updates. Their Hebrew articles say the exact reverse - that the Pfizer vaccine is very effective against the South African variant, yet still a garbage newspaper.
Original ynet English Article: https://www.ynetnews.com/health_science/article/HJMpKyeLO