JOHANNESBURG - A two-dose Pfizer/BioNTech vaccination provides just 33% protection against infection by the omicron variant of the coronavirus, but 70% protection against hospitalization, according to a large-scale analysis in South Africa released Tuesday.The first large-scale analysis of vaccine effectiveness in the region where the new variant was discovered appears to support early indications that omicron is more easily transmissible and that the Pfizer shot isn't as effective in protecting against infection as it was against the delta variant.The analysis was based on more than 211,000 positive COVID-19 test results, 41% from adults who had received two doses of the Pfizer vaccine.