5.3.8 Other therapies
Hydrogen peroxide (H2O2) appears to be
another potential therapeutic option for COVID-19. Of note, health
experts have said that this compound could help prevent the virus from
spreading across the body and from causing damage (Darwin Malicdem,
2020). A recent study illustrated that even just 0.5% of hydrogen
peroxide could kill human coronaviruses, such as those that caused SARS
and MERS (Kampf et al., 2020). Inhaling the vapor with a nebulizer has
been the most convenient way to receive
H2O2 to fight viral infections. The
microscopic mist can easily penetrate the nostrils, sinuses, and lungs,
which are commonly affected by respiratory diseases like COVID-19.
Besides, molecular hydrogen has been verified to favorably modulate the
generation of both O2- and NO through
influencing NADPH oxidase, and the NOS enzymes (TW, LeBaron, McCullough
ML, 2020). According to the National Health Commission of China, the
conditional use of mixed inhalation of hydrogen and oxygen
(H2/O2: 66.6%/33.3%) treatment may
improve the symptoms (Sohu, 2020).
Lung transplantation can be performed in advanced patients with
respiratory failure owing to COVID-19-related pulmonary fibrosis. As it
is reported in a clinical study, lung transplantation may offer the
ultimate treatment option for severe patients to avoid certain deaths,
while at the same time protecting transplantation doctors and medical
staff appropriately (Chen et al., 2020a).
Development of SARS-CoV-2 vaccines
In terms of controlling the epidemic aroused by emerging viruses, rapid
diagnosis and effective vaccines serve as a complementation to antiviral
therapy. Preventive and therapeutic SARS-CoV-2 vaccines will be of
fundamental value as the most conspicuous way to mitigate the pandemic
crisis (André, 2001). Fortunately, published data on the SARS-CoV-2
genetic sequence has sparked a global campaign to inaugurate a vaccine
against the infections. The scope of the impact of the COVID-19 pandemic
on humanitarianism and the economy is also prompting the assessment of
the next-generation vaccine technology platform through new paradigms.
On March 16, 2020, the first trial of COVID-19 vaccine candidate was
launched in record speed. Moreover, the Coalition for Epidemic
Preparedness Innovations (CEPI) is also combining efforts to espouse the
development of vaccines against COVID-19.
As for the vaccine development of SARS-CoV-2, the pivotal and tangible
avenues can be divided into four aspects: 1) Selection of antigen
epitope. 2) Overcoming the antibody-dependent enhancement (ADE) issue.
3) Weighing humoral immunity and cellular immunity. 4) Selection of
technical route befittingly. Up till now, structural epitope mapping by
homology modeling has uncovered the immunoreactive antigen epitopes of
SARS-CoV-2 (Tilocca et al., 2020). The mainstream of the vaccine
development is based upon the S protein in virtue of its essential role
in the viral infectivity. Other subsequent developments can constrain
focus on other viral proteins (i.e., the N protein, and E protein).
Further, the titers of neutralizing antibodies that were variable among
different patients were associated with the spike-binding Abs targeting
S1, RBD, and S2 regions (Wu et al., 2020a). In this regard, we should
also pay more attention to the titers of neutralizing antibodies.
In addition, researchers need to know whether the vaccine will induce
the same type of immune system failures that have been observed
previously. In some cases, the vaccine-primed immune system seems to
initiate a shoddy response to natural infections (Peeples, 2020).
Additionally, allergic inflammation aroused by Th2 immunopathology
should be taken into consideration, according to the coronavirus experts
(Peeples, 2020). Therefore, animal and human clinical trials of COVID-19
candidate vaccines should encompass a rigorous assessment of possible
immune complications before putting into use.
According to the previous study on SARS-CoV, SARS-specific IgG Ab may
ultimately fade away, and the peripheral memory B cell response cannot
be detected in recovered SARS patients. In stark contrast, the memory
response of specific T cells lasted at least six years, implicating the
significance of cellular immunity for preventing the recurrence
epidemics (Tang et al., 2011).
With regard to the technical routes, we can see efforts to espouse
‘quick-fix’ programs for the purpose of developing vaccines against
COVID-19 worldwide (Jiang, 2020). There is a desperate need for
selecting effective technical routes to develop different kinds of
vaccines (i.e., live-attenuated vaccines, inactivated vaccines, nucleic
acid vaccines, subunit, recombinant, polysaccharide, and conjugate
vaccines) in a quicker and safer manner (HHS.gov, 2020).
As announced by the WHO, there are now more than 70 potential vaccines
under development, with three already in clinical trials (Keown, 2020).
The following section will describe the status of vaccine development
against this crisis by miscellaneous methods. The potential vaccine
candidates for COVID-19 are summarized in Table 2.
Table 2. The potential vaccine candidates for COVID-19 (Le et
al., 2020; Hodgson, 2020; Times, 2020; ARENA, 2020; ChiCTR,
2020).