New research looks at COVID-19 quarantine length in asymptomatic contacts, convalescent plasma for mild disease, related health issues

Seven-day quarantine may be sufficient for contacts without symptoms, older adults with mild disease may benefit from convalescent plasma, and cardiovascular deaths increased during the early stage of the pandemic.


A seven-day rather than a 10-day quarantine period may be sufficient for asymptomatic persons exposed to a patient with confirmed COVID-19, according to a recent study.

A report published Jan. 8 by MMWR looked at the effectiveness of a policy instituted by the Vermont Department of Health in May 2020 allowing persons with confirmed exposure to COVID-19 to end quarantine if they had remained asymptomatic and received a negative result on a polymerase chain reaction test for SARS-CoV-2 on or after day 7. From May 8 to Nov. 16, 2020, the health department identified 8,798 exposed contacts of COVID-19 patients. Of these, 3,983 (45%) had sought testing within 14 days of exposure. In this group, 2,200 (55%) received testing on days 7 to 10, and of these, 977 (44.9%) had a specimen collected on day 7. In the latter group, 34 (3%) had positive results, 940 (96%) had negative results, and three (<1%) had indeterminate results. Twenty-two of the 34 contacts with positive results were symptomatic at testing and 12 were not. One hundred fifty-four of the 940 contacts who received negative results on specimens collected on day 7 had another test within the next seven days, and of these, 152 (99%) received negative results and two (1%) received indeterminate results. Among all of the 2,200 contacts who were tested on days 7 to 10 after exposure, 87 (4%) had a positive result, and of these, 24 (28%) were asymptomatic. The researchers concluded that no quarantined contacts who tested negative at day 7 after exposure and were retested between days 8 and 14 tested positive, indicating that shortening quarantine in asymptomatic persons with a negative test result on day 7 or later has not been shown to result in SARS-CoV-2 transmission. “In addition to reducing the duration of quarantine for exposed contacts, Vermont's policy might have provided additional benefits to the state's pandemic response by identifying some asymptomatic patients earlier in the course of their illness through enhancing statewide surveillance testing of an exposed group,” they wrote. “This assessment supports Vermont's policy as being effective and offers data to support recommendations to shorten quarantine with testing such as those provided in CDC's updated quarantine guidance.”

A small randomized, double-blind, placebo-controlled trial in Argentina indicated that early plasma therapy may be of benefit in older patients with mild COVID-19 disease. One hundred sixty older patients were assigned to receive convalescent plasma with high IgG titers against SARS-CoV-2 or placebo within 72 hours after onset of mild COVID-19 symptoms. The patients were screened at home for SARS-CoV-2 infection and were transferred to a trial hospital for infusions if infection was detected. The primary end point was severe respiratory disease, which was defined as a respiratory rate of at least 30 breaths/min, an oxygen saturation below 93% on ambient air, or both. The trial was stopped early, at 76% of its projected sample size, because decreased cases of COVID-19 in the region precluded steady ongoing enrollment. Results were published Jan. 6 by the New England Journal of Medicine.

In the intention-to-treat population, 13 of 80 patients (16%) who received convalescent plasma developed severe respiratory disease versus 25 of 80 patients (31%) who received placebo (relative risk, 0.52; 95% CI, 0.29 to 0.94; P=0.03). In a modified intention-to-treat analysis that excluded six patients who had a primary end point event before they received convalescent plasma or placebo, the effect size was larger (relative risk, 0.40; 95% CI, 0.20 to 0.81). Patients were monitored for adverse events for 12 hours after infusion; none were detected. The researchers concluded that high-titer convalescent plasma can reduce progression of COVID-19 in older adults with mild illness if administered within 72 hours of symptom onset.

Finally, a study published Jan. 11 by the Journal of the American College of Cardiology found that heart disease deaths increased in some parts of the United States during the early phase of the COVID-19 pandemic. Researchers used data from the National Center for Health Statistics to examine the rate of deaths from March 18 to June 2, 2020, and from Jan. 1 to March 17, 2020, with changes in deaths compared with the same periods in the previous year. From Jan. 1 to June 2, 2020, 397,042 cardiovascular deaths occurred. Deaths from ischemic heart disease increased nationally after the pandemic began versus changes in the same period in 2019 (ratio of the relative change in deaths per 100,000 in 2020 vs. 2019, 1.11 [95% CI, 1.04 to 1.18]), as did deaths from hypertensive disease (1.17 per 100,000 [95% CI, 1.09 to 1.26]). Deaths from heart failure, cerebrovascular disease, or other diseases of the circulatory system did not increase.

When the researchers examined areas that had experienced a large surge of COVID-19 cases, they found a large relative increase in deaths from ischemic heart disease and hypertensive disease in New York City during the pandemic, with more modest increases in the rest of the state and in New Jersey, Michigan, and Illinois but no such increases in Massachusetts or Louisiana. “Our findings suggest that the pandemic may have had an indirect toll on patients with cardiovascular disease, possibly owing to the avoidance of hospitals because of concerns about exposure to the virus, increased strain on health care systems, and deferred outpatient and procedural care,” the authors concluded. An accompanying editorial said that the study highlights the importance of continued investigation of all ancillary effects of COVID-19, including cardiovascular health, mental health, substance abuse, domestic violence, and homelessness. “A heightened understanding of these downstream health implications should inform future public policy decisions and messaging strategies,” the editorialists wrote.