Forecasting and Surveillance of COVID-19 Spread Using Google Trends: Literature Review

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Abstract

The probability of future Coronavirus Disease (COVID)-19 waves remains high, thus COVID-19 surveillance and forecasting remains important. Online search engines harvest vast amounts of data from the general population in real time and make these data publicly accessible via such tools as Google Trends (GT). Therefore, the aim of this study was to review the literature about possible use of GT for COVID-19 surveillance and prediction of its outbreaks. We collected and reviewed articles about the possible use of GT for COVID-19 surveillance published in the first 2 years of the pandemic. We resulted in 54 publications that were used in this review. The majority of the studies (83.3%) included in this review showed positive results of the possible use of GT for forecasting COVID-19 outbreaks. Most of the studies were performed in English-speaking countries (61.1%). The most frequently used keyword was “coronavirus” (53.7%), followed by “COVID-19” (31.5%) and “COVID” (20.4%). Many authors have made analyses in multiple countries (46.3%) and obtained the same results for the majority of them, thus showing the robustness of the chosen methods. Various methods including long short-term memory (3.7%), random forest regression (3.7%), Adaboost algorithm (1.9%), autoregressive integrated moving average, neural network autoregression (1.9%), and vector error correction modeling (1.9%) were used for the analysis. It was seen that most of the publications with positive results (72.2%) were using data from the first wave of the COVID-19 pandemic. Later, the search volumes reduced even though the incidence peaked. In most countries, the use of GT data showed to be beneficial for forecasting and surveillance of COVID-19 spread.

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A novel coronavirus outbreak of global health concern

Chen Wang, Peter W Horby, Frederick G. Hayden … (2020)

In December, 2019, Wuhan, Hubei province, China, became the centre of an outbreak of pneumonia of unknown cause, which raised intense attention not only within China but internationally. Chinese health authorities did an immediate investigation to characterise and control the disease, including isolation of people suspected to have the disease, close monitoring of contacts, epidemiological and clinical data collection from patients, and development of diagnostic and treatment procedures. By Jan 7, 2020, Chinese scientists had isolated a novel coronavirus (CoV) from patients in Wuhan. The genetic sequence of the 2019 novel coronavirus (2019-nCoV) enabled the rapid development of point-of-care real-time RT-PCR diagnostic tests specific for 2019-nCoV (based on full genome sequence data on the Global Initiative on Sharing All Influenza Data [GISAID] platform). Cases of 2019-nCoV are no longer limited to Wuhan. Nine exported cases of 2019-nCoV infection have been reported in Thailand, Japan, Korea, the USA, Vietnam, and Singapore to date, and further dissemination through air travel is likely.1, 2, 3, 4, 5 As of Jan 23, 2020, confirmed cases were consecutively reported in 32 provinces, municipalities, and special administrative regions in China, including Hong Kong, Macau, and Taiwan. 3 These cases detected outside Wuhan, together with the detection of infection in at least one household cluster—reported by Jasper Fuk-Woo Chan and colleagues 6 in The Lancet—and the recently documented infections in health-care workers caring for patients with 2019-nCoV indicate human-to-human transmission and thus the risk of much wider spread of the disease. As of Jan 23, 2020, a total of 835 cases with laboratory-confirmed 2019-nCoV infection have been detected in China, of whom 25 have died and 93% remain in hospital (figure ). 3 Figure Timeline of early stages of 2019-nCoV outbreak 2019-nCoV=2019 novel coronavirus. In The Lancet, Chaolin Huang and colleagues 7 report clinical features of the first 41 patients admitted to the designated hospital in Wuhan who were confirmed to be infected with 2019-nCoV by Jan 2, 2020. The study findings provide first-hand data about severity of the emerging 2019-nCoV infection. Symptoms resulting from 2019-nCoV infection at the prodromal phase, including fever, dry cough, and malaise, are non-specific. Unlike human coronavirus infections, upper respiratory symptoms are notably infrequent. Intestinal presentations observed with SARS also appear to be uncommon, although two of six cases reported by Chan and colleagues had diarrhoea. 6 Common laboratory findings on admission to hospital include lymphopenia and bilateral ground-glass opacity or consolidation in chest CT scans. These clinical presentations confounded early detection of infected cases, especially against a background of ongoing influenza and circulation of other respiratory viruses. Exposure history to the Huanan Seafood Wholesale market served as an important clue at the early stage, yet its value has decreased as more secondary and tertiary cases have appeared. Of the 41 patients in this cohort, 22 (55%) developed severe dyspnoea and 13 (32%) required admission to an intensive care unit, and six died. 7 Hence, the case-fatality proportion in this cohort is approximately 14·6%, and the overall case fatality proportion appears to be closer to 3% (table ). However, both of these estimates should be treated with great caution because not all patients have concluded their illness (ie, recovered or died) and the true number of infections and full disease spectrum are unknown. Importantly, in emerging viral infection outbreaks the case-fatality ratio is often overestimated in the early stages because case detection is highly biased towards the more severe cases. As further data on the spectrum of mild or asymptomatic infection becomes available, one case of which was documented by Chan and colleagues, 6 the case-fatality ratio is likely to decrease. Nevertheless, the 1918 influenza pandemic is estimated to have had a case-fatality ratio of less than 5% 13 but had an enormous impact due to widespread transmission, so there is no room for complacency. Table Characteristics of patients who have been infected with 2019-nCoV, MERS-CoV, and SARS-CoV7, 8, 10, 11, 12 2019-nCoV * MERS-CoV SARS-CoV Demographic Date December, 2019 June, 2012 November, 2002 Location of first detection Wuhan, China Jeddah, Saudi Arabia Guangdong, China Age, years (range) 49 (21–76) 56 (14–94) 39·9 (1–91) Male:female sex ratio 2·7:1 3·3:1 1:1·25 Confirmed cases 835† 2494 8096 Mortality 25† (2·9%) 858 (37%) 744 (10%) Health-care workers 16‡ 9·8% 23·1% Symptoms Fever 40 (98%) 98% 99–100% Dry cough 31 (76%) 47% 29–75% Dyspnoea 22 (55%) 72% 40–42% Diarrhoea 1 (3%) 26% 20–25% Sore throat 0 21% 13–25% Ventilatory support 9·8% 80% 14–20% Data are n, age (range), or n (%) unless otherwise stated. 2019-nCoV=2019 novel coronavirus. MERS-CoV=Middle East respiratory syndrome coronavirus. SARS-CoV=severe acute respiratory syndrome coronavirus. * Demographics and symptoms for 2019-nCoV infection are based on data from the first 41 patients reported by Chaolin Huang and colleagues (admitted before Jan 2, 2020). 8 Case numbers and mortalities are updated up to Jan 21, 2020) as disclosed by the Chinese Health Commission. † Data as of Jan 23, 2020. ‡ Data as of Jan 21, 2020. 9 As an RNA virus, 2019-nCoV still has the inherent feature of a high mutation rate, although like other coronaviruses the mutation rate might be somewhat lower than other RNA viruses because of its genome-encoded exonuclease. This aspect provides the possibility for this newly introduced zoonotic viral pathogen to adapt to become more efficiently transmitted from person to person and possibly become more virulent. Two previous coronavirus outbreaks had been reported in the 21st century. The clinical features of 2019-nCoV, in comparison with SARS-CoV and Middle East respiratory syndrome (MERS)-CoV, are summarised in the table. The ongoing 2019-nCoV outbreak has undoubtedly caused the memories of the SARS-CoV outbreak starting 17 years ago to resurface in many people. In November, 2002, clusters of pneumonia of unknown cause were reported in Guangdong province, China, now known as the SARS-CoV outbreak. The number of cases of SARS increased substantially in the next year in China and later spread globally, 14 infecting at least 8096 people and causing 774 deaths. 12 The international spread of SARS-CoV in 2003 was attributed to its strong transmission ability under specific circumstances and the insufficient preparedness and implementation of infection control practices. Chinese public health and scientific capabilities have been greatly transformed since 2003. An efficient system is ready for monitoring and responding to infectious disease outbreaks and the 2019-nCoV pneumonia has been quickly added to the Notifiable Communicable Disease List and given the highest priority by Chinese health authorities. The increasing number of cases and widening geographical spread of the disease raise grave concerns about the future trajectory of the outbreak, especially with the Chinese Lunar New Year quickly approaching. Under normal circumstances, an estimated 3 billion trips would be made in the Spring Festival travel rush this year, with 15 million trips happening in Wuhan. The virus might further spread to other places during this festival period and cause epidemics, especially if it has acquired the ability to efficiently transmit from person to person. Consequently, the 2019-nCoV outbreak has led to implementation of extraordinary public health measures to reduce further spread of the virus within China and elsewhere. Although WHO has not recommended any international travelling restrictions so far, 15 the local government in Wuhan announced on Jan 23, 2020, the suspension of public transportation, with closure of airports, railway stations, and highways in the city, to prevent further disease transmission. 16 Further efforts in travel restriction might follow. Active surveillance for new cases and close monitoring of their contacts are being implemented. To improve detection efficiency, front-line clinics, apart from local centres for disease control and prevention, should be armed with validated point-of-care diagnostic kits. Rapid information disclosure is a top priority for disease control and prevention. A daily press release system has been established in China to ensure effective and efficient disclosure of epidemic information. Education campaigns should be launched to promote precautions for travellers, including frequent hand-washing, cough etiquette, and use of personal protection equipment (eg, masks) when visiting public places. Also, the general public should be motivated to report fever and other risk factors for coronavirus infection, including travel history to affected area and close contacts with confirmed or suspected cases. Considering that substantial numbers of patients with SARS and MERS were infected in health-care settings, precautions need to be taken to prevent nosocomial spread of the virus. Unfortunately, 16 health-care workers, some of whom were working in the same ward, have been confirmed to be infected with 2019-nCoV to date, although the routes of transmission and the possible role of so-called super-spreaders remain to be clarified. 9 Epidemiological studies need to be done to assess risk factors for infection in health-care personnel and quantify potential subclinical or asymptomatic infections. Notably, the transmission of SARS-CoV was eventually halted by public health measures including elimination of nosocomial infections. We need to be wary of the current outbreak turning into a sustained epidemic or even a pandemic. The availability of the virus' genetic sequence and initial data on the epidemiology and clinical consequences of the 2019-nCoV infections are only the first steps to understanding the threat posed by this pathogen. Many important questions remain unanswered, including its origin, extent, and duration of transmission in humans, ability to infect other animal hosts, and the spectrum and pathogenesis of human infections. Characterising viral isolates from successive generations of human infections will be key to updating diagnostics and assessing viral evolution. Beyond supportive care, 17 no specific coronavirus antivirals or vaccines of proven efficacy in humans exist, although clinical trials of both are ongoing for MERS-CoV and one controlled trial of ritonavir-boosted lopinavir monotherapy has been launched for 2019-nCoV (ChiCTR2000029308). Future animal model and clinical studies should focus on assessing the effectiveness and safety of promising antiviral drugs, monoclonal and polyclonal neutralising antibody products, and therapeutics directed against immunopathologic host responses. We have to be aware of the challenge and concerns brought by 2019-nCoV to our community. Every effort should be given to understand and control the disease, and the time to act is now. This online publication has been corrected. The corrected version first appeared at thelancet.com on January 29, 2020

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COVID-19: what is next for public health?

David L. Heymann, Nahoko Shindo (2020)

The WHO Scientific and Technical Advisory Group for Infectious Hazards (STAG-IH), working with the WHO secretariat, reviewed available information about the outbreaks of 2019 novel coronavirus disease (COVID-19) on Feb 7, 2020, in Geneva, Switzerland, and concluded that the continuing strategy of containment for elimination should continue, and that the coming 2–3 weeks through to the end of February, 2020, will be crucial to monitor the situation of community transmission to update WHO public health recommendations if required. Genetic analysis early in the outbreak of COVID-19 in China revealed that the virus was similar to, but distinct from, severe acute respiratory syndrome coronavirus (SARS-CoV), but the closest genetic similarity was found in a coronavirus that had been isolated from bats. 1 As there was in early January, 2020, scarce information available about the outbreak, knowledge from outbreaks caused by the SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV) formed the basis for WHO public health recommendations in mid-January. 2 However, the availability of more evidence in the past month has shown major differences between the outbreaks and characteristics of COVID-19 compared with those of SARS-CoV. Recognising the Wuhan-focused and nationwide outbreak responses in China, WHO has encouraged countries with heavy air travel exchange with Wuhan to take precautionary public health measures 2 and, if there is imported infection, to undertake activities that could lead to the elimination of the virus in human populations as occurred during the 2003 SARS outbreak. 3 After the SARS outbreak, a few follow-on outbreaks occurred, including accidents in laboratories researching SARS-CoV. 4 SARS-CoV is thought to have been eliminated from human populations during 2003, and there have been no reports in the medical literature about SARS-CoV circulation in human populations since then. The 2003 SARS outbreaks are thought to have originated from the spillover of a mutated coronavirus from animals sold in a live animal market in Guangdong province in China to a few humans, and it then surfaced as a large cluster of pneumonia in health-care settings in Guangdong province. 5 Although the causative agent was then unknown, an infected medical doctor who had been treating patients in Guangdong province travelled to Hong Kong when he became ill and became an index case for hospital-associated and community outbreaks in Hong Kong and in three countries outside of China. The causative agent was later identified as a coronavirus and named SARS-CoV. The SARS outbreaks were at times characterised by several superspreading events—eg, hotel-based transmission from one infected hotel guest to others who travelled to Canada, Singapore, and Vietnam. 6 One large apartment complex-based outbreak of SARS was later found to be caused by aerosolisation of virus contaminated sewage. 6 COVID-19 is thought to have been introduced to human populations from the animal kingdom in November or December, 2019, as suggested by the phylogeny of genomic sequences obtained from early cases. 7 The genetic epidemiology suggests that from the beginning of December, 2019, when the first cases were retrospectively traced in Wuhan, the spread of infection has been almost entirely driven by human-to-human transmission, not the result of continued spillover. There was massive transmission in a matter of weeks in Wuhan, and people in the resulting chains of transmission spread infection by national and international travel during the Chinese New Year holidays. COVID-19 seems to have different epidemiological characteristics from SARS-CoV. COVID-19 replicates efficiently in the upper respiratory tract and appears to cause less abrupt onset of symptoms, similar to conventional human coronaviruses that are a major cause of common colds in the winter season. 8 Infected individuals produce a large quantity of virus in the upper respiratory tract during a prodrome period, are mobile, and carry on usual activities, contributing to the spread of infection. By contrast, transmission of SARS-CoV did not readily occur during the prodromal period when those infected were mildly ill, and most transmission is thought to have occurred when infected individuals presented with severe illness, thus possibly making it easier to contain the outbreaks SARS-CoV caused, unlike the current outbreaks with COVID-19. 6 © 2020 Kyodo News/Contributor/Getty Images 2020 Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active. COVID-19 also has affinity for cells in the lower respiratory tract and can replicate there, causing radiological evidence of lower respiratory tract lesions in patients who do not present with clinical pneumonia. 8 There seem to be three major patterns of the clinical course of infection: mild illness with upper respiratory tract presenting symptoms; non-life-threatening pneumonia; and severe pneumonia with acute respiratory distress syndrome (ARDS) that begins with mild symptoms for 7–8 days and then progresses to rapid deterioration and ARDS requiring advanced life support (WHO EDCARN clinical telephone conference on COVID-19, personal communication with Myoung-don Oh [Seoul National University Hospital] and Yinzhong Shen [Shanghai Public Health Clinical Center]) The case fatality ratio with COVID-19 has been difficult to estimate. The initial case definition in China included pneumonia but was recently adjusted to include people with milder clinical presentation and the current estimate is thought to be about 1–2%, which is lower than that for SARS (10%). 9 The actual case fatality ratio of infection with COVID-19 will eventually be based on all clinical illness and at the time of writing information on subclinical infection is not available and awaits the development of serological tests and serosurveys. Presently COVID-19 seems to spread from person to person by the same mechanism as other common cold or influenza viruses—ie, face to face contact with a sneeze or cough, or from contact with secretions of people who are infected. The role of faecal–oral transmission is yet to be determined in COVID-19 but was found to occur during the SARS outbreak. 10 The lock-down of Wuhan City seems to have slowed international spread of COVID-19; however, the effect is expected to be short-lived (WHO modelling group). Efforts are currently underway in China, in the 24 countries to which infected persons have travelled, and in public conveyances, such as cruise ships, to interrupt transmission of all existing and potential chains of transmission, with elimination of COVID-19 in human populations as the final goal. This WHO-recommended strategy is regularly assessed each week by STAG-IH on the basis of daily risk assessments by WHO as information becomes available from outbreak sites. A plausible scenario based on the available evidence now is that the newly identified COVID-19 is causing, like seasonal influenza, mild and self-limiting disease in most people who are infected, with severe disease more likely among older people or those with comorbidities, such as diabetes, pulmonary disease, and other chronic conditions. Health workers and carers are at high risk of infection, and health-care-associated amplification of transmission is of concern as is always the case for emerging infections. People in long-term care facilities are also at risk of severe health consequences if they become infected. Non-pharmaceutical interventions remain central for management of COVID-19 because there are no licensed vaccines or coronavirus antivirals. If the situation changes towards much wider community transmission with multiple international foci, the WHO strategy of containment for elimination could need to be adjusted to include mitigation strategies combined with the following activities currently recommended by STAG-IH on the WHO website. First, close monitoring is needed of changes in epidemiology and of the effectiveness of public health strategies and their social acceptance. Second, continued evolution is needed of enhanced communication strategies that provide general populations and vulnerable populations most at risk with actionable information for self-protection, including identification of symptoms, and clear guidance for treatment seeking. Third, continued intensive source control is needed in the epicentre in China—ie, isolation of patients and persons testing positive for COVID-19, contact tracing and health monitoring, strict health facility infection prevention and control, and use of other active public health control interventions with continued active surveillance and containment activities at all other sites where outbreaks are occurring in China. Fourth, continued containment activities are needed around sites outside China where there are infected people and transmission among contacts, with intensive study to provide information on transmissibility, means of transmission, and natural history of infection, with regular reporting to WHO and sharing of data. Fifth, intensified active surveillance is needed for possible infections in all countries using the WHO-recommended surveillance case definition. 11 Sixth, preparation for resilience of health systems in all countries is needed, as is done at the time of seasonal influenza, anticipating severe infections and course of disease in older people and other populations identified to be at risk of severe disease. Seventh, if widespread community transmission is established, there should then be consideration of a transition to include mitigation activities, especially if contact tracing becomes ineffective or overwhelming and an inefficient use of resources. Examples of mitigation activities include cancelling public gatherings, school closure, remote working, home isolation, observation of the health of symptomatic individuals supported by telephone or online health consultation, and provision of essential life support such as oxygen supplies, mechanical ventilators and extracorporeal membrane oxygenation (ECMO) equipment. Eighth, serological tests need to be developed that can estimate current and previous infections in general populations. Finally, continued research is important to understand the source of the outbreak by study of animals and animal handlers in markets to provide evidence necessary for prevention of future coronavirus outbreaks.

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Predicting COVID-19 Incidence Through Analysis of Google Trends Data in Iran: Data Mining and Deep Learning Pilot Study

Seyed Ayyoubzadeh, Seyed Mehdi Ayyoubzadeh, Hoda Zahedi … (2020)

Background The recent global outbreak of coronavirus disease (COVID-19) is affecting many countries worldwide. Iran is one of the top 10 most affected countries. Search engines provide useful data from populations, and these data might be useful to analyze epidemics. Utilizing data mining methods on electronic resources’ data might provide a better insight into the COVID-19 outbreak to manage the health crisis in each country and worldwide. Objective This study aimed to predict the incidence of COVID-19 in Iran. Methods Data were obtained from the Google Trends website. Linear regression and long short-term memory (LSTM) models were used to estimate the number of positive COVID-19 cases. All models were evaluated using 10-fold cross-validation, and root mean square error (RMSE) was used as the performance metric. Results The linear regression model predicted the incidence with an RMSE of 7.562 (SD 6.492). The most effective factors besides previous day incidence included the search frequency of handwashing, hand sanitizer, and antiseptic topics. The RMSE of the LSTM model was 27.187 (SD 20.705). Conclusions Data mining algorithms can be employed to predict trends of outbreaks. This prediction might support policymakers and health care managers to plan and allocate health care resources accordingly.