LONDON (AP) — House-by-house COVID-19 testing has begun in some communities in England as authorities try to extinguish a new variant of the coronavirus before it spreads widely and undermines a nationwide vaccination program. Authorities want to reach the 80,000 residents of eight areas where the variant first identified in South Africa is known to be spreading. They are dispatching home testing kits and mobile testing units in an effort to reach every resident of those communities. Public health officials are concerned about the variant first identified in South Africa because it contains a mutation of the virus’ characteristic spike protein that existing vaccines target. The mutation may mean the vaccines offer less protection against the variant.