Becker's Clinical Quality & Infection Control

7 INFECTION CONTROL Herd immunity for COVID-19 is still far off, research suggests By Mackenzie Bean T he world is still a long way away from achiev- ing herd immunity for COVID-19, according to research cited by The New York Times. The exact threshold needed to achieve herd immunity is still unknown. Many epidemiologists predict that at least 60 percent of the population will need to develop resistance to hit this threshold. Studies looking at antibody testing results offer some insight into the world's progress toward this target. Sweden limited lockdowns this spring to try to build up immunity among residents quicker. But only 7.3 percent of people in Stockholm are estimated to have antibodies, according to a survey from the city's public health agency. In New York City — once the epicenter of the pandemic — about 19.9 percent of people had antibodies as of early May. Collectively, this research revealed that we are unlikely to reach herd immunity "any time soon," Michael Mina, MD, PhD, an epidemiologist at the Harvard T.H. Chan School of Public Health in Boston, told the Times. n Positive COVID-19 tests after recovery can be 'red herring,' expert says By Anuja Vaidya T esting people multiple times aer they've recovered from COVID-19 may not be a useful practice, as these tests can be a "red herring," Michael Osterholm, PhD, a public health expert told STAT News. Dr. Osterholm is director of the University of Minnesota's Center for Infectious Diseas- es Research and Policy in Minneapolis. He is among experts who doubt the value of using reverse transcription polymerase chain reac- tion testing on patients who have recovered from COVID-19 and continuing to test them until the test comes back negative. ere have been several cases worldwide where a person has continued to test positive for COVID-19 aer recovery. For example, a mother tested positive for COVID-19 for 55 days aer her baby was born at a hospital in Montreal, Canada. As a result, she was not able to hold or nurse her newborn for nearly two months. Some studies are also showing that some recovered COVID-19 patients, tested using polymerase chain reaction, will continue to test positive for long periods, STAT reported. Polymerase chain reaction tests can identify fragments of virus DNA, but they cannot determine if a person is shedding the whole virus that can be transmitted to other people and infect them, or if they are only shedding viral debris that is not infectious. Health officials in South Korea studied 285 COVID-19 patients who recovered and later tested positive for the virus. ey found these patients were not infectious and could not transmit the virus. "It's a red herring," said Dr. Osterholm about testing using reverse transcription polymerase chain reaction aer COVID-19 recovery, according to STAT. "Because what it leads us to believe is something that very likely is not true, and that is that we're still shedding infectious virus." n Vaccinations fall; CDC warns of possible measles outbreak By Gabrielle Masson R outine vaccinations for young children in the U.S. dropped after a national emergency was declared March 13 in response to the COVID-19 pandemic, potentially exposing vulnerable individuals to measles and other vaccine-preventable diseases, according to the CDC's Morbidity and Mortality Weekly Report published May 18. Researchers analyzed immunization data for children 1 to 24 months old in Michigan, where a stay-at-home order was is- sued March 23, and compared it to data from 2016 through 2019. The analysis found that all vaccinations dropped, except for hepatitis B, which is typically given at birth. Recommended vaccinations for 5 month-olds fell from about two-thirds of children from 2016 through 2019 to few- er than half at a point of time in May 2020, the report found. The drop in vaccination coverage may leave young chil- dren and communities vulnerable to vaccine-preventable diseases. If 90 percent to 95 percent of the population is not vaccinated against measles, outbreaks can occur, the CDC warned. More than 117 million children in 37 countries may miss out on receiving measles vaccines amid the pandemic, with measles immunization campaigns delayed in at least 24 countries, according to an April 14 release by Measles and Rubella Initiative, a global partnership aimed at ensuring no child dies from measles or rubella. n

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