geneva the world health organisation says coronavirus case counts fell 17 per cent worldwide over the last week compared to the previous week including a 50 per cent drop in the united states while deaths globally declined 7 per centthe weekly epidemiological report from the un health agency released late tuesday shows that the omicron variant is increasingly dominant making up nearly 97 per cent of all cases tallied by the international virustracking platform known as gisaid just over 3 per cent were of the delta variantthe prevalence of the omicron variant has increased globally and is now detected in almost all countries who saidhowever many of the countries which reported an early rise in the number of cases due to the omicron variant have now reported a decline in the total number of new cases since the beginning of january 2022all told who reported more than 19 million new cases of covid19 and under 68000 new deaths during the week from january 31 to february 6 as with all such tallies experts say such figures are believed to greatly underestimate the real tollcase counts fell in each of whos six regions except its eastern mediterranean zone which reported a 36 per cent jump notably with increases in afghanistan iran and jordanin europe case counts fell 7 per cent led by declines in places like france and germany even as countries in eastern europe like azerbaijan belarus and russia posted increases in the americas case counts fell 36 per cent with the united states still the single mostaffected country reporting 187 million new cases down 50 per cent from the previous weekwho cited limited data about the effectiveness of vaccines against the omicron variant while saying estimates showed reduced protection of the first series of covid19 vaccines against the variant for severe disease symptomatic disease and infection vaccines were most effective to prevent severe disease from omicronthe agency said booster doses increase estimates of vaccine effectiveness to over 75 per cent for all vaccines for which data are available though the rates declined after three to six months after injection