Long-COVID Symptoms in Individuals Infected with Different SARS-CoV-2 Variants of Concern: A Systematic Review of the Literature
Abstract
:1. Introduction
2. Methods
2.1. Search Strategy
2.2. Selection Criteria
- Population: Adults (>18 years) previously infected with SARS-CoV-2 and diagnosed with real-time reverse transcription-polymerase chain reaction (RT-PCR) assay or serological test. Subjects could have been hospitalized or not by SARS-CoV-2 acute infection. One group should have been infected with Alpha (B.1.1.7), Delta (B.1.617.2) or Omicron (B.1.1.529/BA.1) variants. We included studies defining the particular variant of concern based on genomic sequencing or the time period of predominance in each particular country.
- Intervention: Not applicable.
- Comparison: Articles should investigate the presence of long-COVID symptoms in at least one SARS-CoV-2 variant of concern that is different from the historical strain.
- Outcome: Collection of long-COVID symptoms developed after SARS-CoV-2 infection by personal, telephone or electronic interviews. We considered any long-COVID symptom, e.g., fatigue, dyspnea, pain, brain fog, memory loss, skin rashes, palpitations, cough, and sleep problems. We included all studies regardless of the definition of long-COVID used.
2.3. Screening Process, Study Selection and Data Extraction
2.4. Methodological Quality
2.5. Data Synthesis
3. Results
3.1. Study Selection
3.2. Sample Characteristics
3.3. Methodological Quality
3.4. Long-COVID Symptoms by SARS-CoV-2 Variant
4. Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Acknowledgments
Conflicts of Interest
References
- Parra-Lucares, A.; Segura, P.; Rojas, V.; Pumarino, C.; Saint-Pierre, G.; Toro, L. Emergence of SARS-CoV-2 variants in the world: How could this happen? Life 2022, 12, 194. [Google Scholar] [CrossRef]
- Thye, A.Y.; Law, J.W.; Pusparajah, P.; Letchumanan, V.; Chan, K.G.; Lee, L.H. Emerging SARS-CoV-2 Variants of Concern (VOCs): An Impending Global Crisis. Biomedicines 2021, 9, 1303. [Google Scholar] [CrossRef]
- Tani-Sassa, C.; Iwasaki, Y.; Ichimura, N.; Nagano, K.; Takatsuki, Y.; Yuasa, S.; Takahashi, Y.; Nakajima, J.; Sonobe, K.; Nukui, Y.; et al. Viral loads and profile of the patients infected with SARS-CoV-2 Delta, Alpha, or R.1 variants in Tokyo. J. Med. Virol. 2022, 94, 1707–1710. [Google Scholar] [CrossRef]
- Teyssou, E.; Delagrèverie, H.; Visseaux, B.; Lambert-Niclot, S.; Brichler, S.; Ferre, V.; Marot, S.; Jary, A.; Todesco, E.; Schnuriger, A.; et al. The Delta SARS-CoV-2 variant has a higher viral load than the Beta and the historical variants in nasopharyngeal samples from newly diagnosed COVID-19 patients. J. Infect. 2021, 83, e1–e3. [Google Scholar] [CrossRef]
- Karim, S.S.A.; Karim, Q.A. Omicron SARS-CoV-2 variant: A new chapter in the COVID-19 pandemic. Lancet 2021, 398, 2126–2128. [Google Scholar] [CrossRef]
- Hoang, V.T.; Colson, P.; Levasseur, A.; Delerce, J.; Lagier, J.C.; Parola, P.; Million, M.; Fournier, P.E.; Raoult, D.; Gautret, P. Clinical outcomes in patients infected with different SARS-CoV-2 variants at one hospital during three phases of the COVID-19 epidemic in Marseille, France. Infect Genet. Evol. 2021, 95, 105092. [Google Scholar] [CrossRef]
- Park, S.; Lim, S.Y.; Kim, J.Y.; Park, H.; Lim, J.S.; Bae, S.; Kim, J.; Jung, J.; Kim, M.J.; Chong, Y.P.; et al. Clinical and virological characteristics of SARS-CoV-2 B.1.617.2 (Delta) variant: A prospective cohort study. Clin. Infect. Dis. 2022, 75, e27–e34. [Google Scholar] [CrossRef]
- Fernández-de-las-Peñas, C. Long COVID: Current definition. Infection 2022, 50, 285–286. [Google Scholar] [CrossRef]
- Soriano, J.B.; Murthy, S.; Marshall, J.C.; Relan, P.; Diaz, J.V.; WHO Clinical Case Definition Working Group on Post-COVID-19 Condition. A clinical case definition of post-COVID-19 condition by a Delphi consensus. Lancet Infect. Dis. 2022, 22, e102–e107. [Google Scholar] [CrossRef]
- Fernández-de-las-Peñas, C.; Palacios-Ceña, D.; Gómez-Mayordomo, V.; Florencio, L.L.; Cuadrado, M.L.; Plaza-Manzano, G.; Navarro-Santana, M. Prevalence of Post-COVID-19 symptoms in hospitalized and non-hospitalized COVID-19 survivors: A systematic review and meta-analysis. Eur. J. Int. Med. 2021, 92, 55–70. [Google Scholar] [CrossRef]
- Han, Q.; Zheng, B.; Daines, L.; Sheikh, A. Long-term sequelae of COVID-19: A systematic review and meta-analysis of one-year follow-up studies on post-COVID symptoms. Pathogens 2022, 11, 269. [Google Scholar] [CrossRef]
- Chen, C.; Haupert, S.R.; Zimmermann, L.; Shi, X.; Fritsche, L.G.; Mukherjee, B. Global prevalence of post COVID-19 condition or long COVID: A meta-analysis and systematic review. J. Infect. Dis. 2022, 226, 1593–1607. [Google Scholar] [CrossRef]
- Malik, P.; Patel, K.; Pinto, C.; Jaiswal, R.; Tirupathi, R.; Pillai, S.; Patel, U. Post-acute COVID-19 syndrome (PCS) and health-related quality of life (HRQoL)—A systematic review and meta-analysis. J. Med. Virol. 2022, 94, 253–262. [Google Scholar] [CrossRef]
- Wise, J. COVID-19: Two million people in the UK are estimated to be experiencing long COVID, says ONS. BMJ 2022, 377, o1391. [Google Scholar] [CrossRef]
- Wilson, C. Long COVID risk with omicron may be half that of delta. New Sci. 2022, 254, 12. [Google Scholar] [CrossRef]
- Wise, J. COVID-19: Long COVID risk is lower with omicron than delta, researchers find. BMJ 2022, 377, o1500. [Google Scholar] [CrossRef]
- Ward, H.; Flower, B.; Garcia, P.J.; Ong, S.W.X.; Altmann, D.M.; Delaney, B.; Smith, N.; Elliott, P.; Cooke, G. Global surveillance, research, and collaboration needed to improve understanding and management of long COVID. Lancet 2021, 398, 2057–2059. [Google Scholar] [CrossRef]
- Crook, H.; Raza, S.; Nowell, J.; Young, M.; Edison, P. Long COVID: Mechanisms, risk factors, and management. BMJ 2021, 374, n1648. [Google Scholar] [CrossRef]
- Maglietta, G.; Diodati, F.; Puntoni, M.; Lazzarelli, S.; Marcomini, B.; Patrizi, L.; Caminiti, C. Prognostic factors for post-COVID-19 syndrome: A systematic review and meta-analysis. J. Clin. Med. 2022, 11, 1541. [Google Scholar] [CrossRef]
- Gao, P.; Liu, J.; Liu, M. Effect of COVID-19 vaccines on reducing the risk of long COVID in the real world: A systematic review and meta-analysis. Int. J. Environ. Res. Public Health 2022, 19, 12422. [Google Scholar] [CrossRef]
- Page, M.J.; McKenzie, J.E.; Bossuyt, P.M.; Boutron, I.; Hoffmann, T.C.; Mulrow, C.D.; Shamseer, L.; Tetzlaff, J.M.; Akl, E.A.; Brennan, S.E.; et al. The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ 2021, 372, n7. [Google Scholar]
- Wells, G.A.; Tugwell, P.; O’Connell, D.; Welch, V.; Peterson, J.; Shea, B. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies in meta-analyses. 2015. [Google Scholar]
- Antonelli, M.; Pujol, J.C.; Spector, T.D.; Ourselin, S.; Steves, C.J. Risk of long COVID associated with delta versus omicron variants of SARS-CoV-2. Lancet 2022, 399, 2263–2264. [Google Scholar] [CrossRef]
- Morioka, S.; Tsuzuki, S.; Suzuki, M.; Terada, M.; Akashi, M.; Osanai, Y.; Kuge, C.; Sanada, M.; Tanaka, K.; Maruki, T.; et al. Post COVID-19 condition of the Omicron variant of SARS-CoV-2. J. Infect. Chemother. 2022, 28, 1546–1551. [Google Scholar] [CrossRef]
- Azzolini, E.; Levi, R.; Sarti, R.; Pozzi, C.; Mollura, M.; Mantovani, A.; Rescigno, M. Association between BNT162b2 vaccination and long COVID after infections not requiring hospitalization in health care workers. JAMA 2022, 328, 676–678. [Google Scholar] [CrossRef]
- Fernández-de-las-Peñas, C.; Cancela-Cilleruelo, I.; Rodríguez-Jiménez, J.; Gómez-Mayordomo, V.; Pellicer-Valero, O.J.; Martín-Guerrero, J.D.; Hernández-Barrera, V.; Arendt-Nielsen, L.; Torres-Macho, J. Associated-onset symptoms and post-COVID-19 symptoms in hospitalized COVID-19 survivors infected with Wuhan, Alpha or Delta SARS-CoV-2 variant. Pathogens 2022, 11, 725. [Google Scholar] [CrossRef]
- Arjun, M.C.; Singh, A.K.; Roy, P.; Ravichandran, M.; Mandal, S.; Pal, D.; Das, K.; Alekhya, G.; Venkateshan, M.; Mishra, B.; et al. Long COVID following Omicron wave in Eastern India—A retrospective cohort study. J. Med. Virol. 2022. [Google Scholar] [CrossRef]
- Qasmieh, S.A.; Robertson, M.M.; Teasdale, C.A.; Kulkarni, S.G.; Jones, H.; McNairy, M.; Borrell, L.N.; Nash, D. The prevalence of SARS-CoV-2 infection and long COVID in US adults during the BA.5 surge, June–July 2022. medRxiv 2022. [Google Scholar] [CrossRef]
- National Institute for Health and Care Excellence (NICE); Royal College of General Practitioners; Healthcare Improvement Scotland SIGN. COVID-19 Rapid Guideline: Managing the Long-Term Effects of COVID-19; National Institute for Health and Care Excellence: London, UK, 2020; Available online: www.nice.org.uk/guidance/ng188 (accessed on 30 October 2022).
- Fernández-de-las-Peñas, C.; Rodríguez-Jiménez, J.; Cancela-Cilleruelo, I.; Guerrero-Peral, A.; Martín-Guerrero, J.D.; García-Azorín, D.; Cornejo-Mazzuchelli, A.; Hernández-Barrera, V.; Pellicer-Valero, O.J. Post-COVID-19 symptoms 2 years after SARS-CoV-2 infection among hospitalized vs non-hospitalized patients. JAMA Netw. Open 2022, 5, e2242106. [Google Scholar] [CrossRef]
- O’Sullivan, O. Long-term sequelae following previous coronavirus epidemics. Clin. Med. 2021, 21, e68–e70. [Google Scholar] [CrossRef]
- Menges, D.; Ballouz, T.; Anagnostopoulos, A.; Aschmann, H.E.; Domenghino, A.; Fehr, J.S.; Puhan, M.A. Burden of post-COVID-19 syndrome and implications for healthcare service planning: A population-based cohort study. PLoS ONE 2021, 16, e0254523. [Google Scholar] [CrossRef]
- Fernández-de-las-Peñas, C.; Martín-Guerrero, J.D.; Cancela-Cilleruelo, I.; Moro-López-Menchero, P.; Pellicer-Valero, O.J. Exploring the recovery curve for long-term post-COVID dyspnea and fatigue. Eur. J. Intern Med. 2022, 101, 120–123. [Google Scholar] [CrossRef]
- Mackay, A. A paradigm for post-COVID-19 fatigue syndrome analogous to ME/CFS. Front. Neurol. 2021, 12, 701419. [Google Scholar] [CrossRef]
- Haffke, M.; Freitag, H.; Rudolf, G.; Seifert, M.; Doehner, W.; Scherbakov, N.; Hanitsch, L.; Wittke, K.; Bauer, S.; Konietschke, F.; et al. Endothelial dysfunction and altered endothelial biomarkers in patients with post-COVID-19 syndrome and chronic fatigue syndrome (ME/CFS). J. Transl. Med. 2022, 20, 138. [Google Scholar] [CrossRef]
- Sigal, A. Milder disease with Omicron: Is it the virus or the pre-existing immunity? Nat. Rev. Immunol. 2022, 22, 69–71. [Google Scholar] [CrossRef]
- Sette, A.; Crotty, S. Adaptive immunity to SARS-CoV-2 and COVID-19. Cell 2021, 184, 861–880. [Google Scholar] [CrossRef]
- Lippi, G.; Nocini, R.; Henry, B.M. Analysis of online search trends suggests that SARS-CoV-2 Omicron (B.1.1.529) variant causes different symptoms. J. Infect. 2022, 84, e76–e77. [Google Scholar] [CrossRef]
- Zahra, S.A.; Iddawela, S.; Pillai, K.; Choudhury, R.Y.; Harky, A. Can symptoms of anosmia and dysgeusia be diagnostic for COVID-19? Brain Behav. 2020, 10, e01839. [Google Scholar] [CrossRef]
- Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD). Available online: https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm (accessed on 15 October 2022).
- Notarte, K.I.; Catahay, J.A.; Velasco, J.V.; Pastrana, A.; Ver, A.T.; Pangilinan, F.C.; Peligro, P.J.; Casimiro, M.; Guerrero, J.J.; Gellaco, M.M.L.; et al. Impact of COVID-19 vaccination on the risk of developing long-COVID and on existing long-COVID symptoms: A systematic review. EClinicalMedicine 2022, 53, 101624. [Google Scholar] [CrossRef]
- Penetra, S.L.S.; da Silva, M.F.B.; Resende, P.; Pina-Costa, A.; Santos, H.F.P.; Guaraldo, L.; Calvet, G.A.; Ogrzewalska, M.; Arantes, I.; Zukeram, K.; et al. Post-acute COVID-19 syndrome after reinfection and vaccine breakthrough by the SARS-CoV-2 Gamma variant in Brazil. Int. J. Infect. Dis. 2022, 114, 58–61. [Google Scholar] [CrossRef]
- Lo, C.K.; Mertz, D.; Loeb, M. Newcastle-Ottawa Scale: Comparing reviewers’ to authors’ assessments. BMC Med. Res. Methodol. 2014, 14, 45. [Google Scholar] [CrossRef] [Green Version]
- Tran, V.T.; Riveros, C.; Clepier, B.; Desvarieux, M.; Collet, C.; Yordanov, Y.; Ravaud, P. Development and validation of the long COVID symptom and impact tools, a set of patient-reported instruments constructed from patients’ lived experience. Clin. Infect. Dis. 2022, 74, 278–287. [Google Scholar] [CrossRef]
PubMed Search Formula #1 “post-acute COVID-19 syndrome” [Supplementary Concept] OR “post-acute COVID-19 syndrome” [All Fields] OR “long-COVID” [All Fields] OR “long-COVID symptoms” [All Fields] OR “long hauler” [All Fields] OR “post-COVID-19” [All Fields] OR “post-acute COVID-19 symptoms” [All Fields] OR “COVID-19 sequelae” [All Fields] #2 “SARS-CoV-2 variants” [Supplementary Concept] OR “alpha” [All Fields] OR “B.1.1.7” [All Fields] OR “beta” [All Fields] OR “B.1.351” [All Fields] OR “gamma” [All Fields] OR “P.1” [All Fields] OR “delta” [All Fields] OR “B.1.617.2” [All Fields] OR “omicron” [All Fields] OR “B.1.1.529” [All Fields] #3 #1 AND #2 |
Medline/CINAHL (via EBSCO) Search Formula #1 “post-acute COVID-19 syndrome” OR “long-COVID” OR “long-COVID symptoms” OR “long hauler” OR “post-COVID-19” OR “post-acute COVID-19 symptoms” OR “COVID-19 sequelae” #2 “SARS-CoV-2 variants” OR “alpha” OR “B.1.1.7” OR “beta” OR “B.1.351” OR “gamma” OR “P.1” OR “delta” OR “B.1.617.2” OR “omicron” OR “B.1.1.529” #3 #1 AND #2 |
WOS (EMBASE)/Web of Science Search Formula (“post-acute COVID-19 syndrome” OR “long-COVID” OR “long-COVID symptoms” OR “long hauler” OR “post-COVID-19” OR “post-acute COVID-19 symptoms” OR “COVID-19 sequelae” AND (“SARS-CoV-2 variants” OR “alpha” OR “B.1.1.7” OR “beta” OR “B.1.351” OR “gamma” OR “P.1” OR “delta” OR “B.1.617.2” OR “omicron” OR “B.1.1.529”) |
medRxiv (“post-acute COVID-19 syndrome” OR “long-COVID” OR “long-COVID symptoms” OR “long hauler” OR “post-COVID-19” OR “post-acute COVID-19 symptoms” OR “COVID-19 sequelae” AND (“SARS-CoV-2 variants” OR “alpha” OR “B.1.1.7” OR “beta” OR “B.1.351” OR “gamma” OR “P.1” OR “delta” OR “B.1.617.2” OR “omicron” OR “B.1.1.529”) |
Author | Variant | Country Study Period | Design Sample | Age | Symptoms Assessment | Prevalence of Long-COVID by Variant | Long-COVID Definition |
---|---|---|---|---|---|---|---|
Morioka et al., 2022 [24] | Omicron | Japan Omicron (n = 53) 1 December 2021–9 February 2022 Follow-up: 3 months after Other variants (n = 502) February 2020–November 2021 | Cross-sectional n = 555 Female n = 314 Hospitalized n = 53 | Omicron age 56 (35–69) Other variants age 48 (42–55) | Telephone interviews Self-reporting questionnaire survey | Omicron group At least one post-COVID symptom 5.6% Other variants group At least one post-COVID symptom 55.6% | Symptoms that persisted for at least 2 months within 3 months of COVID-19 onset |
Azzolini et al., 2022 [25] | Historical Alpha Delta–Omicron | Italy March 2020 to April 2022 | Longitudinal observational cohort n = 739 Female n = 551 | NR | Survey questionnaire | OR (95% CI) Wave 1 NR Wave 2 0.72 (0.48–1.08) Wave 3 1.34 (0.26–7.01) | At least one symptom with a duration of more than 4 weeks after the infection |
Qasmieh et al., 2022 [28] | Omicron | United States June 2022–July 2022 | Cross-sectional n = 1036 Female n = 528 Hospitalized NR | Range 18–65 y | Survey via landlines (IVR) and mobile phones (SMS text) | Prevalence (95% CI) 21.5% (18.2–24.7) Men: 15.5 (11.6–19.4) Women: 27.3 (22.2–32.4) Fully vaccinated 25.1% (16.9–33.4) Not vaccinated 22.2% (16.6–27.9) Boosted 19.2% (14.8–23.5) | Symptoms more than 4 weeks after the start of COVID-19 that are not explained by something else |
Antonelli et al., 2022 [23] | Omicron Delta | United Kingdom June 2021–March 2022 | Case-control n = 97,364 Delta (n = 41,361) Omicron (n = 56,003) Female n = 55,205 Hospitalized NR | 53 years | Self-reported data from the COVID Symptom Study app | OR (95% CI) Omicron vs. Delta >6 m post-vaccination 0.26 (0.20–0.32) 3–6 m post-vaccination 0.24 (0.19–0.32) <3 m post-vaccination 0.50 (0.43–0.59) | New or ongoing symptoms 4 weeks or more after acute COVID-19 |
Arjun et al., 2022 [27] | Omicron | India First week of January–middle of February 2022 | Retrospective cohort n = 524 Female n = 212 Hospitalized n = 27 | Age Mean (SD) 36 (14); | Telephone interviews | Prevalence (95% CI) 8.2% (6% to 10.9%) | Post-COVID-19 condition defined as signs and symptoms that develop during or after COVID-19, continue for more than 12 weeks and are not explained by an alternative diagnosis |
Fernández-de-las-Peñas et al., 2022 [26] | Historical (n = 201) Alpha (n = 211) Delta (n = 202) | Spain March 2020–August 2021 | Cross-sectional cohort n = 614 Female n = 327 Hospitalized n = 614 | Mean (SD) Historical 60.5 (15.5) Alpha 70.0 (15.5) Delta 56.5 (21.0) | Telephone interviews | Historical variant Number symptoms: 2.7 ± 1.3 Fatigue 68.2% Dyspnea 29.35% Alpha variant Number symptoms: 1.8 ± 1.1 Fatigue 71.5% Dyspnea 13.75% Delta variant Number symptoms: 2.1 ± 1.5 Fatigue 76.35% Dyspnea 12.8% | Development of symptoms 6 months after the acute phase of the infection |
Study | Selection | Comparability | Exposure | Score | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Adequate Case Definition | Representativeness of Cases | Selection of Controls | Definition of Controls | Controlled for Age | Controlled for Additional Factors | Ascertainment of Exposure | Same Method for Cases and Controls | Non-Response Rate | ||
Antonelli et al., 2022 [23] | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 9/9 |
Study | Selection | Comparability | Outcome | Score | ||||||
Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposure | Outcome of interest was not present at the start of the study | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome | Was the follow-up long enough for outcomes to occur? | Adequacy of the follow-up of cohorts | |||
Main factor | Additional factor | |||||||||
Marioka et al., 2022 [24] | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7/9 | ||
Azzolini et al., 2022 [25] | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7/9 | ||
Qasmieh et al., 2022 [28] | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 8/9 | |
Arjun et al., 2022 [27] | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7/9 | ||
Fernández-de-las-Peñas et al., 2022 [26] | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 8/9 |
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
Fernández-de-las-Peñas, C.; Notarte, K.I.; Peligro, P.J.; Velasco, J.V.; Ocampo, M.J.; Henry, B.M.; Arendt-Nielsen, L.; Torres-Macho, J.; Plaza-Manzano, G. Long-COVID Symptoms in Individuals Infected with Different SARS-CoV-2 Variants of Concern: A Systematic Review of the Literature. Viruses 2022, 14, 2629. https://doi.org/10.3390/v14122629
Fernández-de-las-Peñas C, Notarte KI, Peligro PJ, Velasco JV, Ocampo MJ, Henry BM, Arendt-Nielsen L, Torres-Macho J, Plaza-Manzano G. Long-COVID Symptoms in Individuals Infected with Different SARS-CoV-2 Variants of Concern: A Systematic Review of the Literature. Viruses. 2022; 14(12):2629. https://doi.org/10.3390/v14122629
Chicago/Turabian StyleFernández-de-las-Peñas, César, Kin Israel Notarte, Princess Juneire Peligro, Jacqueline Veronica Velasco, Miguel Joaquín Ocampo, Brandon Michael Henry, Lars Arendt-Nielsen, Juan Torres-Macho, and Gustavo Plaza-Manzano. 2022. "Long-COVID Symptoms in Individuals Infected with Different SARS-CoV-2 Variants of Concern: A Systematic Review of the Literature" Viruses 14, no. 12: 2629. https://doi.org/10.3390/v14122629