COVID-19 (novel coronavirus): What we know, what we don’t know, and how we can plan within our communities March 5, 2020 Andrew Lover, MS MPH PhD Dept. of Biostatistics and Epidemiology [email protected] School of Public Health and Health Sciences Updated Mar 7; v1.1. Overview 1. Some background 2. The virus and epidemiology 3. Response measures and community preparedness 4. Q & A School of Public Health and Health Sciences 2 Disclaimers All opinions in this talk are my personal views, and do not represent those of the Department of Biostatistics and Epidemiology; the School of Public Health and Health Sciences; or UMass-Amherst. Guidance is being rapidly updated; always consult your local, state and federal authorities for the most up-to-date information. (mass.gov and cdc.gov) General note: most/many current studies are preprints and are not yet peer reviewed; and data change hourly/daily. School of Public Health and Health Sciences 3 Terminology § Coronaviruses are a small class of human pathogens; four of which cause ‘normal’ respiratory infections. § Two others may cause severe infections: SARS-CoV, and MERS-CoV. MERS-CoV § Original name (Jan 2020): Wuhan flu or novel coronavirus-2019 § Current standard (allows for expansion) § Illness: COVID-19 (“coronavirus disease”) § Virus: SARS-CoV-2 § This structure parallels HIV/AIDS School of Public Health and Health Sciences 4 Population-level metrics § Endemic: The constant presence of a disease or infectious agent within a given geographic area or population group § Epidemic: The occurrence in a community or region of cases of an illness clearly in “excess of normal expectancy” (preferred) § Outbreak: An epidemic limited to localized increase in the incidence of a disease (avoid) § Pandemic: An epidemic occurring over a very wide area, crossing international boundaries and usually affecting a large number of people (national or global), but no specific criteria School of Public Health and Health Sciences 5 The first signal…. (Dec 2019) School of Public Health and Health Sciences 6 Ancient history…. Jan 23. Jan 30. School of Public Health and Health Sciences 7 Current status § We’ve moved from a handful of infections in Central China to this, in 8-9 weeks. Source: JHU https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html School of Public Health and Health Sciences 8 Describing individuals § Susceptible: uninfected, but able to become infected if exposed § Infectious: infected and able to transmit the infection to other susceptible individuals § Immune: possessing cell-mediated or humoral antibody protection against an infection § Infected/ill/clinical case: presence of clinical signs (not synonymous with infected) § Subclinical (latent) infection: presence of infectious agent but absence of clinical disease § Carrier: implies a protracted infected state with shedding of the infectious agent. Carriers may be diseased, recovering, or healthy. School of Public Health and Health Sciences 9 The ID Epi Iceberg (why is surveillance difficult?) Symptoms Data quality - Generally good - Severe Clinical - Moderate disease - Generally good - Mild? Subclinical - Moderate to poor disease - Poor without - None? specific studies - None. - Very poor School of Public Health and Health Sciences 10 The epidemiological triad § A dynamic system, with many modifiable components. Human host • Age and sex • Behavior • Nutritional status • Health status Agent Environment • Infectivity • Weather • Pathogenicity • Housing • Virulence • Geography • Immunogenicity • Occupational setting • Antigenic stability • Political situation • Survival • Infrastructure School of Public Health and Health Sciences 11 Quantifying infections How fast? Attack rate -----> (number with clinical illness / number exposed) x 100 How serious? Case fatality ratio (ability to cause death in clinical cases) -----> (number of deaths / number with clinical disease) x 100 Infection fatality ratio (ability to cause death in all infections) -----> (number of deaths / number infected) x 100 School of Public Health and Health Sciences 12 Reproductive number R0 The basic reproductive number, R0, the mean number of individuals directly infected by an infectious case through the total infectious period, when introduced into a fully susceptible population. probability of transmission per contact R0 = p • c • d duration of infectiousness contacts per unit time Infections will….. disappear, if R < 1 become endemic, if R ~ 1 become epidemic, if R > 1 School of Public Health and Health Sciences 13 Reproductive number R0- II § Useful summary statistic, but context-specific, and modifiable. § Some examples: Seasonal influenza: ~ 1.2 EBV disease: ~ 2.2 (2014) COVID-19: 2.3; 1.2-3.5; & others. Measles: 7.7 to 18 (various studies) COVID-19: https://www.ncbi.nlm.nih.gov/pubmed/32097725 School of Public Health and Health Sciences 14 COVID-19 Epidemiology School of Public Health and Health Sciences 15 Is it “Just the flu”? COVID-19 Seasonal influenza § No one has any immunity. § High levels of diverse partial § Case fatality rate estimates: immunity in the community. 1.0 to 2.5% (?). § Case fatality rate: 0.1%. § Many severe cases requiring § Some severe cases (ca. 1.1% critical care (20-25%). for current season). § No vaccine; no antivirals. § Annual vaccine; multiple § Novel pathogen, with no antiviral regimens. clinical or epidemiological § Well-studied pathogens, with evidence-base. decades of clinical and epidemiological guidance. Updated Mar 7: source https://www.cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm School of Public Health and Health Sciences 16 Model-based estimates (LSHTM) § Reporting systems and data completeness varies, so biases are probable. https://cmmid.github.io/ School of Public Health and Health Sciences 17 Most comprehensive data to date School of Public Health and Health Sciences 18 Case demographics § From WHO-China Joint report, based on 55,924 laboratory-confirmed cases: § Age: median 51 years (range: 2 days-100 years old). § Vast majority of cases (77.8%) between 30–69 years. § 51.1% are male. § 21.6% are farmers or laborers. School of Public Health and Health Sciences 19 Joint Mission report- Case fatality ratio Cases of Daily Number Number WHO-China Joint Mission report Feb 2020 Days Since First Case https://reliefweb.int/report/china/report-who-china-joint-mission-coronavirus-disease-2019-covid-19 School of Public Health and Health Sciences 20 Joint Mission report- spectrum of illness Cases of Daily Number Number WHO-China Joint MissionDays Since report First FebCase 2020 https://reliefweb.int/report/china/report-who-china-joint-mission-coronavirus-disease-2019-covid-19 School of Public Health and Health Sciences 21 COVID-19 Symptoms § From WHO-China Joint mission report, based on 55,924 laboratory-confirmed cases: § Reported symptoms (all non-specific): fever (87.9%), dry cough (67.7%), fatigue (38.1%), sputum production (33.4%), shortness of breath (18.6%), sore throat (13.9%), headache (13.6%), myalgia or arthralgia (14.8%), chills (11.4%), nausea or vomiting (5.0%), nasal congestion (4.8%), diarrhea (3.7%), bloody sputum (0.9%), and conjunctival congestion (0.8%). § Symptom onset: mean of 5-6 days after reported exposure (range 1-14 days). School of Public Health and Health Sciences 22 China CDC; (JAMA, 2020) Cases of Daily Number Number Days Since First Case School of Public Health and Health Sciences 23 Droplets versus airborne transmission Droplets “Airborne spread has not been reported for COVID-19 and it is not Aerosol believed to be a major driver of transmission based on available evidence…” WHO-China Joint Mission report Feb 2020 Close contact/ droplet range: ~ 6 ft. Image: https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-019-3707-y School of Public Health and Health Sciences 24 What we don’t know § R0 in dense urban settings outside of Asia. § CFR with all outcomes measured. § CFR in weak health systems with limited critical care facilities. § Size of the asymptomatic/subclincial populations. § Basis and implications of low infections in children. § Potential for reinfection. § Clinical predictors of severity (triage) and optimal treatment protocols. § Potential for long-term impacts (sequelae). School of Public Health and Health Sciences 25 Community measures- a.k.a things you can do right now School of Public Health and Health Sciences 26 Every epidemic is unique § The global and national evidence-base for planning and response is based on influenza and not COVID-19. § Seasonal influenza ≠ influenza pandemic § SARS/COVID-19 ≠ influenza pandemic § However, there are important lessons and commonalities. School of Public Health and Health Sciences 27 General response options Transmission interventions • Infection control Non- Contact interventions pharmaceutical • Social distancing interventions (NPIs) • Quarantine/isolation • Closure of schools/business etc. -------------------------------------------------------------------- Vaccines • Longer-term Antiviral drugs • Several COVID-19 studies underway School of Public Health and Health Sciences 28 Flattening the epicurve https://preventepidemics.org/coronavirus/?=undefined School of Public Health and Health Sciences 29 Step-by-step layers of preparation 1. Normal things we all should (but maybe don’t) do during flu season (“Rules from preschool”) 2. Simple planning and discussions in your household and neighborhood (EASY) 3. Think and strategize for potential longer-term impacts (Slightly less easy) Days Since First