The Times artice on Novavax's recombinant SARS-CoV-2 protein vaccine (delivered with an adjuvant to enhance uptake in the body) is excellent. Goes into great detail on the ~90% efficacy (in preventing symptomatic COVID, post 2nd shot, like the mRNA vaccines) of the phase III trials (15,000 patients) in the UK, as well as the vaccine being just about as good against the UK variant, but as you noted, the efficacy in the much smaller (4400 patients) South African trial was about 50% in all patients and 60% in non-HIV patients, indicating that the SA variant was likely able to "escape" prevention by the vaccine. However, as far as I can tell, there were no serious infections in vaccinated people.
https://www.nytimes.com/2021/01/28/health/covid-vaccine-novavax-south-africa.html
As I posted on the other day, both Moderna and Pfizer are already proactively updating their mRNA vaccines to be able to deal with the UK/SA and Brazilian variants if needed, presumably via a 3rd booster shot for those who are vaccinated and by including the new mRNA snippets in the baseline vaccine for future recipients (so 2 doses would still be enough) - although Pfizer and Moderna still expect their vaccines to be similarly effective against these variants, based on lab studies (but this isn't the same as repeating clinical trials). The article also speculates that J&J's delay in sharing results from the clinical trials may be due to less effectiveness in a South African trial. Results are now expected early next week.
The announcement from Novavax raises the stakes for Johnson & Johnson. The company was expected to announce its results as early as last weekend, and the delay has triggered speculation among scientists that the firm has also discovered that its vaccine worked less well in South African trial volunteers who were infected with the variant. In an earnings call on Tuesday, Alex Gorsky, the chief executive officer of the company, said they were looking forward to sharing results from their late-stage trial by early next week.