Adolescent marijuana use and binge drinking did not significantly change during the COVID-19 pandemic, despite record decreases in the substances’ perceived availability, according to a survey of 12th graders in the United States. The study’s findings, which appeared online on June 24, 2021, in Drug and Alcohol Dependence, challenge the idea that reducing adolescent use of drugs can be achieved solely by limiting their supply. The work was led by researchers at the University of Michigan, Ann Arbor, and funded by the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health (NIH).
In contrast to consistent rates of marijuana and alcohol use, nicotine vaping in high school seniors declined during the pandemic, along with declines in perceived availability of vaping devices at this time. The legal purchase age is 21 for nicotine products and alcohol in all states, and for cannabis in states that have legalized nonmedical cannabis use.
“Last year brought dramatic changes to adolescents’ lives, as many teens remained home with parents and other family members full time,” said NIDA Director Nora D. Volkow, M.D. “It is striking that despite this monumental shift and teens’ perceived decreases in availability of marijuana and alcohol, usage rates held steady for these substances. This indicates that teens were able to obtain them despite barriers caused by the pandemic and despite not being of age to legally purchase them.”
The data for the study came from the annual Monitoring the Future (MTF) survey of substance use behaviors and related attitudes among adolescents in the United States. In a typical year, MTF surveys thousands of middle and high school students at more than a hundred schools across the country in the spring. MTF has been watching substance use trends for 46 years.
To assess the impact of the pandemic, the investigators issued a survey between mid-July and mid-August 2020, which 12th graders could complete outside of school. This summer survey followed up on investigators’ standard MTF spring survey, which gathered responses between mid-February and mid-March 2020 before stopping prematurely due to school closures caused by COVID-19. Of the 3,770 12th graders who responded in the spring, 582 submitted a follow-up survey in the summer. All data and statistical analyses used in the study were weighted to be nationally representative.
Analysis of the responses revealed that students perceived a sharp decrease in availability of marijuana and alcohol in the months after the onset of the pandemic. For marijuana, the fraction of students who reported “fairly” or “very” easy access dropped by 17 percentage points, from 76% in the spring before the pandemic to 59% during the pandemic, and for alcohol it dropped by 24 percentage points, from 86% to 62%. These were the largest year-to-year decreases in perceived availability of marijuana and alcohol ever recorded since the survey began in 1975. Prior to 2020, the largest recorded decreases were only two percentage points for marijuana, and one percentage point for alcohol. Between the spring and summer of 2020, there was also a sharp decrease in respondents who said they could “fairly” or “very” easily obtain a vaping device, going from 73% before the pandemic to 63% during the pandemic.
Despite the reported declines in marijuana and alcohol availability, the levels of use of these substances did not change significantly. Before the pandemic, 23% of students said they had used marijuana in the past 30 days, compared to 20% during the pandemic. For alcohol, 17% reported binge drinking in the past two weeks pre-pandemic, compared to 13% during the pandemic. However, there was a moderate and significant decrease in nicotine vaping – before the pandemic, 24% of respondents said they had vaped nicotine in the past 30 days, compared to 17% during the pandemic.
The study authors cite the wide availability of alcohol and marijuana, even during the pandemic, as a factor in the continued use of these substances. While pandemic-related restrictions limited social interactions, and even with record-breaking decreases in perceived availability among participants, most students said they still had access to marijuana and alcohol. In addition, the authors suggest that when the substances became less available, the students may have intensified their efforts to obtain them.
While a dip in the perceived supply of vaping devices may have contributed to the decline in nicotine vaping that occurred during the pandemic, there may have been other factors as well. The federal minimum age for tobacco product purchases, including vaping devices and liquids, rose from 18 to 21 years and went into effect in early 2020. News reports on vaping-induced lung injuries may have also had a chilling effect on usage.
“These findings suggest that reducing adolescent substance use through attempts to restrict supply alone would be a difficult undertaking,” said Richard A. Miech, Ph.D., lead author of the paper and team lead of the Monitoring the Future study at the University of Michigan. “The best strategy is likely to be one that combines approaches to limit the supply of these substances with efforts to decrease demand, through educational and public health campaigns.”
Monitoring the Future continues to survey respondents as they progress through adulthood, providing the researchers with the opportunity to explore the impact of the pandemic and the social changes it brought about on future substance use trends.
Researchers estimate nearly 17 million undiagnosed cases in the U.S. by mid-July 2020.
In a new study, National Institutes of Health (NIH) researchers report that the prevalence of COVID-19 in the United States during spring and summer of 2020 far exceeded the known number of cases and that infection affected the country unevenly. For every diagnosed COVID-19 case in this time frame, the researchers estimate that there were 4.8 undiagnosed cases, representing an additional 16.8 million cases by July alone. The team’s analysis of blood samples from people who did not have a previously diagnosed SARS-CoV-2 infection, along with socioeconomic, health, and demographic data, offers insight into the undetected spread of the virus and subgroup vulnerability to undiagnosed infection.
“This study helps account for how quickly the virus spread to all corners of the country and the globe,” said Bruce Tromberg, Ph.D., director of the National Institute of Biomedical Imaging and Bioengineering (NIBIB), one of the NIH institutes who run the NIH SARS-CoV-2 Seroprevalence Project. “The information will be invaluable as we assess the best public health measures needed to keep people safe, as new—and even more transmissible—variants emerge and vaccine antibody response changes over time.”
In addition to NIBIB, the research team includes scientists from the National Institute of Allergy and Infectious Diseases (NIAID), the National Center for Advancing Translational Sciences (NCATS); and the Frederick National Laboratory for Cancer Research, sponsored by the National Cancer Institute (NCI). Their report in the June 22, 2021, early online issue of Science Translational Medicine represents the first data from the 12-month NIH study that was launched in April 2020.
“A hallmark of the coronavirus pandemic is that there are people infected with the virus that causes COVID-19 who have few or no symptoms,” said Matthew J. Memoli, M.D., M.S., director, Clinical Studies Unit, Laboratory of Infectious Diseases, NIAID. “While counting the numbers of symptomatic people in the United States is essential to contend with the impact of the pandemic and public health response, gaining a full appreciation of the COVID-19 prevalence requires counting the people who are undiagnosed.”
COVID-19 illness can range from short-lived cough, fatigue and fever to severe illness that could lead to hospitalization and death. Asymptomatic SARS-CoV-2 infection, which is rarely diagnosed, is a silent source of viral spread. While not causing overt signs of illness, undiagnosed infection poses a danger to the public and is a critical factor necessitating public health resources and strategies for addressing the pandemic.
The team recruited over 240,000 volunteers from across the country, then selected 8,058 individuals from that pool through quota sampling to ensure that their study cohort was representative of the U.S. population. Each participant received a sample kit to return to NIH with a dab of dried blood or had blood drawn at NIH, most of which they supplied in an 11-week span between May 10 and July 31. Participants also completed a questionnaire that enabled further analysis of the study results.
The researchers used an enzyme-linked immunosorbent assay to detect antibodies that recognize protein regions from the SARS-CoV-2 virus, referred to as antigens. Antibodies in a blood sample can bind to these antigens. The team found that 304 of the approximately 8,000 blood samples were seropositive, meaning that they contained antibodies against the SARS-CoV-2 virus. The researchers estimated that 4.6% of U.S. adults had undiagnosed COVID-19 during their study period. They determined that each diagnosed case of COVID-19 corresponds to an estimated 4.8 undiagnosed cases of the disease during this time frame.
The team observed that:
the youngest participants—those between the ages of 18 and 44—had the highest estimated seropositivity, at 5.9%,
estimated seropositivity was higher in females than in males (5.5% versus 3.5%, respectively),
participants in the Mid-Atlantic and Northeast regions had the highest rates (8.6% and 7.5%, respectively), and participants in the Midwest had the lowest rates (1.6%),
urban participants had a higher estimated seropositivity (5.3%) compared with rural participants (1.1%), and
Black/African American respondents had the highest estimated seropositivity rate (14.2%), followed by Native American/Alaska Native (6.8%), Hispanic (6.1%), white/Caucasian (2.5%), and Asian (2%) respondents.
“The estimate of COVID-19 cases in the United States in mid-July 2020, 3 million in a population of 330 million, should be revised upwards by almost 20 million when the percent of asymptomatic positive results is included,” said senior co-author Kaitlyn Sadtler, Ph.D., chief of the NIBIB Section on Immunoengineering. “This wide gap between the known cases at the time and these asymptomatic infections has implications not only for retrospectively understanding this pandemic, but future pandemic preparedness.”
The researchers are currently following up with the enrolled participants to evaluate the six- and 12-month status of seroprevalence; it will include new analyses to differentiate antibodies from infection versus antibodies from vaccination, as well as antibody reactivity to variants of concern.
The new report is part of the NIH SARS-CoV-2 Seroprevalence Project. The collaboration includes research groups led by Matthew J. Memoli, M.D., at NIAID; Matthew D. Hall, Ph.D., Early Translation Branch at NCATS; Dominic Esposito, Ph.D., Protein Expression Laboratory at the Frederick National Laboratory for Cancer Research; and Sadtler, Section on Immunoengineering, NIBIB.
This research was supported in part by the NIH Intramural Research Program, funded in part under contract number HHSN261200800001E, 75N91019D00024, Task Order No. 75N91019F00130, Clinical and Translational Science Awards Program grants UL1TR003096 (Robert P. Kimberly, M.D., University of Alabama at Birmingham) and UL1TR001857 (Steven E. Reis, M.D., University of Pittsburgh).
